The investigation into the terror attack that killed five Israelis and a Bulgarian national in the city of Burgas last week has yielded concerns that the same perpetrator behind the attack was headed to London to attack the Israeli delegation at the upcoming Olympic Games, the British Daily Mail reported on Sunday.

According to the Daily Mail, the suspect, believed to be using the name of David Jefferson and carrying an American passport, allegedly helped the suicide bomber who blew himself up near a bus carrying Israeli tourists at Burgas airport. Jefferson is reported to have another powerful bomb similar to the one which destroyed the bus.

Israeli security officials have reason to believe that the Bulgaria attack was the latest in a number of attempted revenge attacks orchestrated by Iran over the assassinations of Iranian nuclear scientists, for which Tehran blames Israel.

Following the suicide bomber's autopsy, his identity is still unclear. Dr. Galina Melba, a forensic expert who took part in the autopsy, said that the body did not match the description provided by many eyewitnesses. This contradiction raised the possibility that perhaps the witnesses saw his accomplice, who is thought to still be at large, and not the bomber himself.

The hunt for the accomplice is ongoing — a police composite sketch of the suspect has been distributed in the entire area. According to reports, the suspect lived in the Bulgarian city of Varna and he was spotted at Varna airport late last month. It was reported Sunday that there may have been a third accomplice who served as a commander for the operation. The third man allegedly carried a gun meant to shoot the suicide bomber in case he changed his mind and decided not to detonate the bomb.

Meanwhile, Israeli officials stressed the importance of security surrounding the Israeli delegation to the Olympics and Israelis abroad in general. Mossad chief Tamir Pardo, and the head of the Israel Security Agency Yoram Cohen briefed the cabinet on Sunday on their efforts to thwart terror attacks targeting Israelis abroad.

Pardo and Cohen related the latest details to emerge from the Burgas attack investigation, saying that Iran and Hezbollah had attempted more than 20 attacks against Israelis over the last year.

Prime Minister Benjamin Netanyahu conferred with British Prime Minister David Cameron on Sunday, ahead of the Olympics. According to the Sunday Times, the Mossad has beefed up its forces in London in efforts to prevent attacks on Israeli athletes. Netanyahu declined to comment on the report.

Defense Minister Ehud Barak also addressed the issue Sunday, saying that "there is definitely intelligence awareness ahead of the Olympics. British security authorities, which are extremely good, are doing their best to minimize the chances of an incident at the Olympics."

Meanwhile, a Kuwaiti publication reported this week that Hezbollah Secretary-General Hassan Nasrallah, who rarely leaves his bunker for fear of assassination, has been relocated to a new hiding place.