The government is working with airlines to bring thousands of Britons home from the Egyptian resort Sharm el-Sheikh after it suspended flights to the UK.
All flights were grounded after US and UK intelligence suggested a bomb may have caused a Russian jet from Sharm to crash killing all 224 people on board.
UK Foreign Secretary Philip Hammond said security would be tightened and it is hoped flights will resume on Friday.
The UK government’s emergency committee Cobra is to meet later.
The decision to suspend flights came as the Egyptian President, Abdel Fattah al-Sisi, arrived in the UK for talks with Prime Minister David Cameron.
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Mr Hammond said there were 19 flights scheduled for Britain from Sharm on Thursday, but none would depart.
“But the airlines are telling us that they expect by tomorrow they’ll be in a position to start flying those British visitors back to the UK,” he said.
“We’re spending today with the airlines, with the Egyptian authorities, putting in place short-term emergency measures that will allow us to screen everything going on to those planes, double-check those planes, so that we can be confident that they can fly back safely to the UK.”
In other developments:
- Transport Secretary Patrick McLoughlin is expected to make a Commons statement on the security situation at Sharm, while Mr Cameron will chair the Cobra meeting
- Extra UK consular staff have been drafted in to Sharm airport
- A US official told the Associated Press news agency they had reached the “tentative conclusion”, after intercepting communications, that an affiliate of the Islamic State group in the Sinai peninsula had planted an explosive device on the plane
- Egyptian officials said the cockpit voice recorder of the Metrojet plane was badly damaged in the crash but they managed to extract information from the flight data recorder
UK aviation experts had been sent to Sharm el-Sheikh to assess the security situation after the Metrojet Airbus 321, bound for St Petersburg, came down in the Sinai desert on Saturday.
Their findings were considered in a one-hour Cobra meeting on Wednesday evening, chaired by Mr Cameron.
Mr Hammond said: “We have concluded there was a significant possibility that that crash was caused by an explosive device on board the aircraft.”
The UK government was “very reluctantly” advising against all but essential travel through Sharm el-Sheikh airport, he said.
A number of travel operators responded to the announcement:
- Thomas Cook cancelled its flight and holiday programme to Sharm el-Sheikh until 12 November
- Thomson Airways along with First Choice, cancelled all outbound flights to Sharm el-Sheikh up to and including 12 November
- British Airways postponed its Thursday flights to and from Sharm el-Sheikh until Friday
- EasyJet cancelled all flights to and from the resort on Thursday and is keeping future flights “under review”
- Monarch cancelled all flights in and out of Sharm el-Sheikh on Thursday
- The Irish Aviation Authority said it had directed Irish airlines not to fly to or from the area until further notice
Mr Hammond stressed the Foreign Office was not changing the travel advice with regard to the Sharm el-Sheikh resort itself, which it views as safe.
The Association of British Travel Agents estimates at least 9,000 of the 20,000 Britons currently in Sharm are holidaymakers.
An Abta spokeswoman said holidaymakers in Sharm and people due to travel to the resort are advised to contact their travel company.
“Most insurance policies will still provide cover for holidaymakers in a country at the time of Foreign Office advice change,” she added.
“Those people with bookings beyond this are advised to wait until closer to the departure date to contact their travel company as the situation is reviewed.”
Egypt’s foreign minister, Sameh Shoukry, said he was very disappointed by the decision to suspend flights, accusing the UK government of making “a premature and unwarranted statement” on the crash.
Egypt has dismissed claims by militants linked to the Islamic State group that they brought down the plane while Russian experts say it is too early to reach a conclusion.
Mr Hammond apologised for the “immense disruption and inconvenience” caused by the decision but said the safety and security of British nationals had to be “above all other considerations”.
He said the UK would be working with the Egyptian authorities and airlines to help put long term sustainable security measures in place.