An Internet virus attacked computers at industrial sites in southern Iran, in an apparent extension of a covert cyber war that initially targeted the country's nuclear facilities, an Iranian official said.

Iran, the world's No. 5 oil exporter, has tightened online security since its uranium enrichment centrifuges were hit in 2010 by the Stuxnet computer worm, which Tehran believes was planted by Israel or the United States.

The unit tasked with fighting cyberattacks, the Passive Defense Organization, said a virus had infected several sites in Hormozgan province in recent months but was neutralized.

"Enemies are constantly attacking Iran's industrial units through Internet networks in order to create disruptions," Ali Akbar Akhavan, head of the Hormozgan branch of the organization, was quoted as saying by the Iranian Students' News Agency on Tuesday.

"This virus has even penetrated some manufacturing industries in Hormozgan province, but with timely measures and the cooperation of skilled hackers in the province, the progress of this virus was halted," Akhavan said.

"As an example, the Bandar Abbas Tavanir Co., a producer of electricity in the province and even adjacent provinces, has been the target of Internet attacks in recent months," he said.

Israeli officials have threatened military action against Iranian nuclear facilities if Western sanctions on Tehran's banking and oil sectors do not persuade the Islamic Republic to shelve its disputed atomic program.

Meanwhile, a summit of Gulf Arab leaders came to a close on Tuesday in Bahrain with participating countries demanding that Iran end what they called interference in Gulf Arab affairs, reiterating the six U.S. allies' long-held mistrust of their regional rival.

A communiqué issued at the end of a two-day summit of the six-member Gulf Cooperation Council (GCC) also called on the international community to bring a swift end to massacres and violations of international law in Syria.

"The council expressed its rejection and condemnation of the continuing Iranian interference in the affairs of the Gulf Cooperation Council's states and called on Iran to stop these policies," the statement said.

Apart from Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates are the other members.

Bahraini Foreign Minister Khalid Bin Ahmed Bin Mohammed Al Khalifa told reporters Iran posed a "very serious threat."

"Politically, (there is) lots of meddling in the affairs of GCC states; an environmental threat to our region from the technology used inside nuclear facilities; and there is of course the looming nuclear program," he said, referring to Iran's disputed atomic work.

So the threat level is quite high, but we are ready if faced with circumstances that require action."

Khalifa also expressed his country's backing for the United Arab Emirates, which claims three islands administered by Iran.

Iran rejected the accusations on Wednesday, saying those countries were "running away from reality", an Iranian news agency reported.

Iranian Foreign Ministry spokesman Ramin Mehmanparast said, "Shifting the responsibility for the domestic problems of the regional countries is a way of running away from reality, and blaming others or using oppressive methods are not the right ways to answer civil demands," he said, according to the Iranian Students' News Agency (ISNA).

The official Islamic Republic News Agency reported that Iran plans to hold naval maneuvers in international waters near the strategic Strait of Hormuz, where one-fifth of world oil supply passes.

The report quoted Iran's navy chief, Adm. Habibollah Sayyari, as saying the maneuvers will begin Friday from the Strait of Hormuz to the northern part of Indian Ocean in an area of about 1 million square kilometers (400,000 square miles).

Iran in the past threatened to close the strait over Western sanctions aimed at its suspect nuclear program but has not repeated the threat lately.

Sayyari said Iran will test-fire missiles and deploy vessels and submarines during the six-day war games.

The semiofficial Fars news agency reported that the navy of the powerful Revolutionary Guards began a limited naval drill Tuesday in central part of the Persian Gulf.

It said the four-day maneuver is meant to test and assess its forces and includes missile firing, the report said.