David Cameron has said he will discuss the Russian plane crash in Sinai in a phone call with Vladimir Putin.
Speaking at the end of a meeting of the Government's Cobra committee, Mr Cameron said it now appeared the crash was "more likely than not" caused by a bomb.
The Prime Minister was set to meet the Egyptian President Abdul Fattah al-Sisi later on Thursday, who has expressed frustration at Britain's decision to cancel flights to and from Sharm el-Sheikh in response to the disaster.
Mr Cameron said he would be discussing Egyptian concerns about security and tourism with President Sisi. But he also said he "puts the safety of British people first".
Mr Cameron said Britain was "working round the clock" on security in Egypt so people could be brought back to the UK, adding that it would "take some time before we can fly people home out of Sharm el-Sheikh".
He said he also feels "huge sympathy for British holidaymakers" and those who would be unable to fly out to Egypt as planned.
Asked about the fact that dozens of Russian flights continued to arrive in Sharm el-Sheikh on Thursday, Mr Cameron said it is "a matter for the Russians" as to whether or not they continue to fly.
He said it was "right to stop our planes" because of the intelligence he has been shown, and says he will discuss "all of this" with President Putin.
"The action he takes will be a matter for him," he said.
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