More countries have joined the UK in curbing travel to the Egyptian resort of Sharm el-Sheikh, amid fears that a bomb brought down a Russian plane on Saturday, killing all 224 on board.
France, Belgium and the Netherlands warned their nationals not to travel, and German airlines cancelled flights.
UK airlines will start to repatriate tourists on Friday, but with hand luggage only.
Militants linked to Islamic State (IS) have claimed they destroyed the plane.
"We brought it down by God's help, but we are under no obligation to reveal the mechanism we used," IS affiliate Sinai Province said in a audio statement circulating on social media on Wednesday.
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The cause of the crash is still unclear and Russia - which is carrying out air strikes against IS in Syria - has warned against pre-empting the outcome of the official investigation.
British authorities stopped flights to and from the resort on Wednesday, saying intelligence suggested the disaster may have been caused by a bomb on board.
UK Prime Minister David Cameron said on Thursday that he had to put the security of British citizens first.
Britons due to return from Sharm el-Sheikh on Friday's UK-bound flights have been told their hold baggage will be transported separately.
France is advising its citizens against all but essential travel to Sharm el-Sheikh, and the Netherlands is warning against travelling via the resort's airport.
Belgium's foreign minister told Belgian TV (in French) that the government was temporarily advising against trips to Sharm el-Sheikh while it awaited guarantees on airport security.
German airline Lufthansa says its subsidiaries Edelweiss and Eurowings are halting flights to Sharm el-Sheikh (from Zurich and Duesseldorf respectively) as a "precautionary" measure, and return flights for customers already there will be arranged.
Russian planes are still flying to and from the resort.
Image copyrightRussian Emergency Ministry
Image copyrightRussian Emergency MinistryUS President Barack Obama told a CBS radio station that he thought there was "a possibility" that there was a bomb on the downed jet.
"We're taking that very seriously," he said.
Egypt's Tourism Minister Hisham Zaazou described the British decision to cancel all flights "unjustified".
Egyptian President Abdul Fattah al-Sisi, in London for talks with Mr Cameron, said Egypt was ready to co-operate on other countries' security concerns.
Egypt is leading the investigation into the air disaster, with the help of Russian and other foreign experts.
They would examine the wreckage for traces of explosives but not reach their first conclusions for a few months, said Alexander Neradko, head of Russia's aviation agency.
The first funerals of victims of the crash were held in Russia on Thursday.
