The crash of a Russian passenger jet in Egypt was "more likely than not" caused by a bomb, British Prime Minister David Cameron said on Thursday.
"It looks increasingly likely that that was the case," Cameron said of the possibility of a bomb on board the plane, on which 224 people died.
Cameron was speaking to British media after chairing a meeting of his government's emergency committee to discuss security in Egypt following the crash.
Asked about Egypt's contention that it was "premature" and "unwarranted" for Britain to suspend flights to Egypt's Sharm el-Sheikh resort and raise the possibility of a bomb having caused the crash, Cameron said he realised that "tourism is vitally important" to Egypt.
"I want to restore our flights, and our links, as soon as possible," he said.
But he added that the possibility of a bomb behind last weekend's crash had "very important implications" for security and he had to "put the safety of British people first."
He said he would discuss the security issues with Egyptian President Abdel-Fattah al-Sisi in London later Thursday.
Earlier Thursday, Foreign Secretary Philip Hammond said flights could resume between Britain and the Egyptian resort of Sharm el-Sheilkh on Friday.
Following a meeting of the government's emergency committee late Wednesday, Prime Minister David Cameron's office said it was "in our mutual interests to work together to do all we can to get back to normal service."
"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," Hammond told the broadcaster.
"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 onto those planes, double-check those planes, so that we can be confident that they can fly back safely to the UK," he said.
An estimated 20,000 British citizens remain in Sharm el-Sheikh, including at least 9,000 holidaymakers, the broadcaster said.
Hammond said late Wednesday that Britain was "working with the airlines and the Egyptian authorities to put in place emergency procedures and additional screening and additional security" at the airport.
By Bill Smith
