The Turkish reconnaissance plane shot down by Syria over the Mediterranean Sea on Friday was fired at because it had entered Syrian airspace, and the incident was "not an attack," a Syrian Foreign Ministry official said Saturday, in an effort to defuse the episode before it explodes into a regional conflagration.

Turkey has threatened to retaliate over the downing of the plane, but has not said what action it will take. It is continuing to search for the aircraft's two missing pilots.

The shooting of the plane heightened tensions between the two neighboring countries, and signaled that the violence gripping Syria is increasingly bleeding outside its borders. Germany and Iraq were among the countries urging restraint in the region.

Syria and Turkey had cultivated close ties before the Syrian revolt began in March 2011, but since then Turkey has become one of the strongest critics of Syria's regime. Turkey hosts civilian and military Syrian opposition groups, including hundreds of army defectors who are affiliated with the Free Syrian Army and collect food and other supplies to deliver to comrades on smuggling routes.

Turkish authorities also suspect that Syria, which was collaborating with Turkey in its fight against autonomy-seeking Kurdish rebels, is now turning a blind eye to Syria-based Kurdish fighters who belong to the Kurdistan Workers' Party (PKK), considered a terrorist organization in the U.S. and Europe.

The plane, an unarmed F-4, went down in the Mediterranean Sea about eight miles (13 kilometers) from the Syrian coastal town of Latakia, Turkey said. Syria claimed the jet penetrated about 1 kilometer (0.62 miles) into Syrian airspace. It said Syrian forces only realized the plane was Turkish after firing at it.

In a telephone interview with Turkish TV news channel A Haber on Saturday, Syrian Foreign Ministry spokesman Jihad Makdissi said the downing was "not an attack."

"An unidentified object entered our airspace and unfortunately as a result it was brought down. It was understood only later that it was a Turkish plane," A Haber quoted Makdissi as saying in a translation of the interview. "There was no hostile act against Turkey whatsoever. It was just an act of defense for our sovereignty."

Turkish Prime Minister Tayyip Erdogan held two security meetings with senior officials after convening a crisis session on Friday evening.

"Turkey will present its final stance after the incident has been fully brought to light and decisively take the necessary steps," Erdogan's office said.

Turkish President Abdullah Gul conceded that the plane might have unintentionally crossed into Syrian airspace, but said it was "routine" for jets to unintentionally cross borders for short periods. The government has not described the plane's specific mission.

Gul said his government was still investigating what happened, but "no one should have any doubt that whatever [action] is necessary will be taken."

It was not clear if this would involve military retaliation, increased sanctions or other steps such as demands for compensation or an apology.

Turkish Labor and Social Security Minister Faruk Celik said his nation would retaliate "either in the diplomatic field or give other types of response."

"Even if we assume that there was a violation of Syria's airspace — though the situation is still not clear — the Syrian response cannot be to bring down the plane," Celik told reporters. "The incident is unacceptable. Turkey cannot endure it in silence."

Turkish newspapers were less restrained.

"They [the Syrians] will pay the price," said Vatan. The Hurriyet daily said: "He [Syrian President Bashar al-Assad] is playing with fire."

Turkish media at first reported Erdogan on Friday as saying Syria had apologized, but the prime minister later said he could not confirm receiving an apology.

Germany and Iraq urged both countries to remain calm and not let the unrest in Syria become a wider conflict,

"Our main concern is the spillover of the crisis into neighboring countries. No country is immune from this spillover," said Iraqi Foreign Minister Hoshyar Zebari.

Turkey has joined the U.S. and other nations in saying that Assad should step down because of the uprising in his country that has killed thousands of people. Turkey also has set up refugee camps on its border for more than 32,000 Syrians who have fled the fighting.

After an April border shooting incident in which two people in a Turkish refugee camp died, Turkey said it would call on its NATO allies to intervene if it felt its security was being threatened.

Turkish Foreign Minister Ahmet Davutoglu met with military officials Saturday to assess what steps to take and to coordinate the search and rescue operation for the two missing pilots and the plane's wreckage, the Foreign Ministry said. Erdogan was expected to discuss the incident with Turkish opposition party leaders on Sunday, and the foreign minister would make a statement on the same day, an aide said.

A Turkish official said Turkey was examining the plane's radar route and other flight data to ascertain whether the aircraft was flying over Syrian territory when it was shot down. The official spoke to The Associated Press on condition of anonymity, and would provide no further details.

Turkey, which is uneasy about Greek Cypriot gas exploration efforts around Cyprus, is believed to have increased patrols recently over the eastern Mediterranean. Some analysts have speculated that the plane may have been spying on possible PKK rebels near Turkey's border. U.S. Secretary of State Hillary Rodham Clinton earlier this month warned about a massing of Syrian forces near Aleppo, saying such a deployment could be a "red line" for Turkey "in terms of their strategic and national interests."

In Baghdad, Zebari said Saturday that the recent defection of a Syrian pilot to Jordan and the downing of the Turkish jet showed that the Syrian conflict could have far-reaching repercussions.

"If this conflict were to turn into all-out sectarian or civil war, Iraq would be affected, Lebanon would be affected, Jordan would not be immune [and] Turkey could be [affected]," Zebari said.

German Foreign Minister Guido Westerwelle said he was "greatly worried" by the incident, urged a thorough investigation and welcomed Turkey's cool-headed reaction in the immediate aftermath.

U.N. Secretary-General Ban Ki-moon told Davutoglu in a telephone conversation Saturday that he was concerned about the implications of the incident for the region, but commended Turkey for showing restraint in its reaction, said U.N. spokesman Martin Nesirky. Ban urged both sides to address the situation diplomatically, Nesirky said.

Turkish Deputy Prime Minister Bulent Arinc and other government ministers urged restraint. "We must remain calm and collected," he said. "We must not give premium to any provocative speeches and acts."

The leader of Turkey's main opposition party, Kemal Kilicdaroglu, said the downing of the plane was unacceptable, but he also urged calm.

"All diplomatic channels must be kept open. We are expecting a coolheaded assessment of the incident," he said.

Meanwhile, inside Syria, opposition activists reported heavy fighting in Deir al-Zor, the provincial capital of an oil-producing region bordering Iraq 420 kilometers (262 miles) northeast of Damascus. On Saturday, Syria's army battled rebels and shelled neighborhoods in the city, killing at least 28 people, opposition activists said.

The victims, who included three women and several children, were mostly civilians killed when shells hit their houses in the city's old airport and al-Hamidya districts, a source at a city hospital told Reuters.

"The death toll is likely higher. There are more bodies at the morgue, but they have not been identified yet," the source said.

Syria has restricted media access since the start of the uprising, making it hard to verify accounts from authorities or activists.

Loyalist forces have lost control of parts of the surrounding Deir al-Zor province, which borders Iraq's Sunni Muslim heartland, as alliances between Assad's ruling elite and Sunni tribes have collapsed.

The artillery barrage on the old airport area on the edge of the city started late on Friday, following the defection of at least 30 members of the Hajjana, a border force that has a base in the area, opposition campaigners from the city told Reuters. The central Al-Hamidya district came under shelling after Free Syrian Army rebels fought off a tank incursion into the area, they added.

Rebels have been mounting increased attack on roadblocks, tanks and fortifications belonging to loyalist troops in Deir al-Zor, from where a main oil pipeline feeds Syria's two refineries, in the city of Homs and an export terminal on the Mediterranean.

The Syrian Arab Red Crescent also said one of its volunteers was killed in the region while on duty on Friday. He was shot in the head while wearing a uniform clearly marked with the organization's emblem, it said.

On Saturday, Assad issued a decree forming a new government, but it will be headed by a key loyalist and the foreign, defense and interior ministers have all kept their jobs. The new government is headed by Riad Farid Hijab, a former agriculture minister and a loyalist member of the ruling Baath Party.

Assad vowed after the May 7 parliamentary elections to make the government more inclusive of politicians from other parties, but the appointment of Hijab and the decision to keep the key posts unchanged raised questions about the commitment to that pledge.

The opposition boycotted the parliamentary elections, saying they were designed to strengthen Assad's grip on power. Parliament is considered little more than a rubber stamp in Syria, where the president and a tight coterie of advisers hold the real power.

Meanwhile, the British Daily Telegraph reported Thursday that members of Assad's inner circle were making secret plans to defect to the opposition should the revolt critically threaten the regime.

Based on information provided by U.S. officials, The Telegraph said senior military figures in Syria "are understood to be laying down 'exit strategies' and establishing lines of communication with the rebels to discuss how they would be received if they deserted."

The report came after a Syrian air force colonel on Thursday defected, abandoning a mission to attack the city of Dera’a and flying his MiG 21 fighter jet to Jordan.

A senior U.S. official in Washington told The Telegraph that some of those closest to Assad were now preparing to flee. “We are seeing members of Bashar al-Assad’s inner circle make plans to leave,” the official told the British daily.

Some senior officials have even moved large sums of money offshore into Lebanese and Chinese banks and have been in contact with opposition figures and Western governments, The Telegraph reported.

Syrian opposition groups confirmed that they were actively courting help from the U.S. to prompt more defections.

A report in The Guardian over Saudi Arabia's plans to fund rebels in Syria may also add to Assad's concerns.

The report, published on Friday, said Saudi officials were slated to pay the salaries of the Free Syrian Army in efforts to encourage mass defections from Assad's army and to increase pressure on his regime. The move, which senior officials in the U.S. and the Arab world have discussed at length, is believed to be gaining momentum following the delivery of several weapons to rebel forces by Saudi Arabia and Qatar, which have started to make an impact on Syrian battlefields, The Guardian said.