The UK has grounded all flights to and from Sharm el-Sheikh following intelligence that suggests a bomb may have downed the Russian airliner flight KGL9268 last week.
There were 19 flights due to depart from the Red Sea resort on Thursday, but Foreign Secretary Philip Hammond said none would now depart.
Around 20,000 Britons are currently believed to be at Sharm el-Sheikh, including 1,000 residents.
A Number 10 spokesperson said:
“The Prime Minister called President Sisi yesterday evening to discuss what measures the Egyptians are taking to ensure the tightest possible security arrangements at Sharm el-Sheikh airport.
“While the investigation is still ongoing we cannot say categorically why the Russian jet 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.
“In light of this and as a precautionary measure we have decided that flights due to leave Sharm for the UK this evening will be delayed. That will allow time for a team of UK aviation experts, currently travelling to Sharm, to make an assessment of the security arrangements in place at the airport and to identify whether any further action is required. We expect this assessment to be completed tonight.”
The Foreign Office says it is working to resume flights, but currently advises against all but essential travel to the Sinai due to the threat of attacks from an Islamic State affiliated group in the region.
Britain is currently the only country to suspend flights to Sharm el-Sheikh, and Russia says theories about the cause of the plane crash in Sinai remain “speculation” at this stage.