A Russian Emergency Situations Ministry employee examines damaged seats of a passenger jet bound for St. Petersburg in Russia that crashed in Hassana, Egypt.

Britain’s foreign minister said on Monday it is highly likely that a bomb planted by an Islamic State of Iraq and Syria (ISIS) group supporter downed the Russian passenger jet lost over Egypt.

Arriving for talks at the U.S. State Department with his American counterpart John Kerry, Philip Hammond said the definitive cause of the crash would be determined by Egyptian-Russian investigation of the wreckage.

But in the meantime, he warned, the British government had received information about the Oct. 31 disaster that had caused it to suspend flights to the Egyptian resort of Sharm el-Sheikh and to order the evacuation of British tourists there.

Speaking alongside Kerry, Hammond said the pair would discuss “the possibility that the airliner in Sinai was brought down by an explosive device placed on board.”

Earlier, in an interview with CNN, he had gone further.

“We think it was more likely than not an explosive device on the aircraft,” Hammond said of the cause of the crash, which killed all 224 people on board the Russia-bound flight.

“There’s got to be a high probability that ISIS was involved,” he added, using an alternative acronym for the Islamic State network.

“That doesn’t mean that it was a directed attack from ISIS headquarters in Syria,” Hammond said.

“It may have been an individual who was inspired by ISIS who was self-radicalized by looking at ISIS propaganda and was acting in the name of ISIS without necessarily being directed.”

British officials have been criticized by Russia and Egypt for suggesting that a bomb caused the crash before investigations are complete, but Hammond said he was speaking on the basis of information he had received.