London  - Airport security will have to be reviewed in areas where Islamic State militants are active if the air crash in Egypt is found to have been caused by a bomb, British foreign secretary, Philip Hammond has said.
Mr Hammond said increased security could mean extra costs and delays at airports.
Flights from Sharm el-Sheikh to the UK have restarted after being halted in the wake of the crash.
But Britons still in Egypt face waits of two or three days to get home.
All 224 people on the board the Russian Metrojet flight from Sharm el-Sheikh to St Petersburg died when it came down in Sinai on 31 October. Most of the victims were Russian.
The US and the UK have both said intelligence points to the strong possibility the crash was caused by a bomb - militants affiliated to Islamic State, or Isil, have claimed responsibility.
Mr Hammond was asked about the implications for airport security in the Middle East, North Africa and Turkey on The Andrew Marr Show.
He said: "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.
"What we have to do is ensure that airport security everywhere is at its best and that it reflects local conditions. One of the key issues about keeping airports safe is the training, management and motivation of staff."
"That may mean additional costs, it may mean additional delays at airports as people check in." (FA)