U.S, U.K. says Russian jet may have been downed by explosive, halts Sinai flights

British and U.S. officials said Wednesday they have information suggesting the Russian jetliner that crashed in the Egyptian desert may have been brought down by a bomb, and Britain said it was suspending flights to and from the Sinai Peninsula indefinitely.

Intercepted communications played a role in the tentative conclusion that the Islamic State group's Sinai affiliate planted an explosive device on the plane, said a U.S. official briefed on the matter. He spoke on condition of anonymity because he wasn't authorized to discuss intelligence matters publicly.

The official and others said there had been no formal judgment rendered by the CIA or other intelligence agencies, and that forensic evidence from the blast site, including the airplane's black box, was still being analyzed.

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The official added that intelligence analysts don't believe the operation was ordered by Islamic State leaders in Raqqa, Syria. Rather, they believe that if it was a bomb, it was planned and executed by the Islamic State's affiliate in the Sinai, which operates autonomously.

Other officials cautioned that intercepted communications can sometimes be misleading and that it's possible the evidence will add up to a conclusion that there was no bomb.

'Significant possibility'

The Metrojet Airbus A321-200 carrying mostly Russian vacationers from Sharm el-Sheikh back to Russia's second-largest city of St. Petersburg crashed over the Sinai early Saturday, killing all 224 people on board.

British Foreign Secretary Philip Hammond said there was a "significant possibility" the crash was caused by a bomb, and Britain was suspending flights to and from the Sinai resort of Sharm el-Sheikh indefinitely.

Cameron's 10 Downing St. office said late Wednesday that the team's preliminary report "noted that the Egyptian authorities had stepped up their efforts but that more remains to be done."

Downing Steet said it could not say "categorically" why the Russian jet had crashed.

"But as more information has come to light, we have become concerned that the plane may well have been brought down by an explosive device," it said in a statement.

The Irish Aviation Authority followed the British lead and directed Irish airlines to suspend flights to Sharm el-Sheikh Airport and into the airspace of the Sinai Peninsula "until further notice."

The British acted "too soon," said Hany Ramsay, deputy head of Sharm el-Sheikh's airport.

Two U.S. officials told the AP on Tuesday that U.S. satellite imagery detected heat around the jet just before it went down.

The infrared activity could mean many things, including a bomb blast or an engine on the plane exploding due to a malfunction. One of the officials who spoke condition of anonymity because they weren't authorized to discuss the information publicly said a missile striking the jetliner was ruled out, because neither a missile launch nor an engine burn had been detected.

The Islamic State group claimed it had downed the plane because of Moscow's recent military intervention in Syria against the extremist group, but el-Sissi dismissed that as "propaganda" aimed at damaging Egypt's image.

Egypt's Aviation Ministry also said the voice recorder is "partially damaged" and that as a result "a lot of work is required in order to extract data from it."