Airport security around the world will have to be overhauled if it is confirmed the Russian airliner crash in the Sinai was caused by an Islamic State bomb, Foreign Secretary Philip Hammond has warned.
Egyptian investigators have said they have yet to determine whether a noise picked up by the cockpit voice recorder in the final seconds of the flight was the sound of the explosion.
However Mr Hammond reaffirmed that the view of the British authorities that it was "more likely than not" that the crash was the result of a terrorist bomb planted on the aircraft before it took off from Sharm el-Sheikh on October 31.
He said that there would have to be a major re-think of airport security in countries where IS - also referred to as Isil of Isis - is active if it turned out that they were behind the attack.
"If this turns out to be a device planted by an Isil operative or by somebody inspired by Isil then clearly we will have to look again at the level of security we expect to see in airports in areas where Isil is active," he told BBC1's The Andrew Marr Show.
"What we have got to do is ensure that airport security everywhere is at the level of the best and that airport security reflects the local conditions and where there is a higher local threat level that will mean higher levels of security are required.
"That may mean additional costs, it may mean additional delays at airports as people check in."