UK: More Likely than Not, a Bomb Downed the Russian Airliner

More likely than not a bomb allegedly placed on the flight by Islamic State or their supporters is the cause of the Russian airliner accident that killed 224 people on Saturday, alleged British Prime Minister David Cameron on Thursday.

Cameron cited “intelligence and information” that he says indicates that a bomb was the likely cause of the accident.

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An affiliate of Islamic State in Egypt has claimed responsibility for the accident on two occasions. On Wednesday, they took to Twitter to say they downed the plane, but refused to say how.

"We say to the deniers and the doubters: Die from your frustration. We, with God's grace, are the ones who brought it down, and we are not obliged to disclose the mechanism of its demise," the group said.

The Metrojet flight carrying Russian tourist crashed Saturday in Egypt's Sinai Peninsula about 26 minutes after taking off from the Red Sea resort of Sharm el-Sheikh.

Cameron announced all flights to and from the Sinai Peninsula have been grounded, stranding about 20,000 British tourists, who he said would be chartered back to the U.K. in British airplanes. The prime minister claimed the “safety of British people” was first.

"We don't know for certain that it was a terrorist bomb ... (but it's a) strong possibility," Cameron said, adding "There's still an investigation taking place in Egypt. We need to see the results of that investigation."

Egypt's Minister of Civil Aviation, Hossam Kamal, assured Thursday that Egyptian airports comply with international security standards.

In Russia, Dmitry Peskov, spokesperson for President Vladimir Putin said investigators were still working and that they were considering all possible theories.

"One cannot rule out a single theory, but at this point there are no reasons to voice just one theory as reliable – only investigators can do that," Peskov said at a press conference in Moscow.

On Wednesday, the United States said a satellite image of the plane at the time of the accident revealed a heat flash that would indicate that there had been an explosion on board. However, the blast could have been caused by faulty electrical wiring or an engine explosion.