David Cameron has said it is "more likely than not" that a Russian airliner was downed by a terrorist bomb as he defended moves to halt flights to and from Sharm el-Sheikh.
The Prime Minister said he had "every sympathy" with Cairo's anger over the impact on its tourist industry but that the move was "about putting the safety of British people first".
Speaking after chairing a meeting of the Government's Cobra emergency committee, Mr Cameron said he would discuss the situation with Egyptian president Abdel Fatah al-Sisi who is due at Number 10 shortly.
Mr Cameron is also due to talk with Russian president Vladimir Putin by phone about the latest developments.
"The decisions that I am taking are about putting the safety of British people first," Mr Cameron said. "That is why we have suspended flights to Sharm el-Sheikh and that is why it is going to take some time before we can fly people out.
"What we need to put in place is more security at that airport so it is safe to fly people home."