Maids, porters and other hotel staff in Sharm el-Sheikh are being questioned to discover if one of them hid a bomb in the luggage of a passenger on board the doomed Russian holiday flight.
With Egypt "90 per cent certain" that Metrojet Flight 9268 was brought down by a terrorist attack, the hunt for the bomber has widened.
Airport staff have already been interrogated without a breakthrough, and now police are exploring the theory that someone with access to the hotel rooms of Russian tourists could have secreted a bomb in a suitcase.
They are checking the backgrounds of staff who work in hotels where victims of the crash were staying.
An airport official told The Daily Telegraph that a British security team that visited the airport last week was particularly alarmed to find a guard manning an x-ray machine playing with his phone instead of monitoring the scanner. Poor lighting in one corner of the airport was also a concern.
The local police have put in an urgent request for more CCTV cameras at the airport, together with a 24-hour monitoring room to keep check on the site both indoors and out.
The effort to repatriate up to 20,000 Britons from Sharm el-Sheikh continued yesterday, with another 11 UK-bound flights scheduled to have left the resort, but concerns have been raised about the protection of luggage after airport staff said 20,000 bags and cases are piled up at the airport.
British passengers are only allowed to travel with hand baggage, after suspicion fell on a bomb being placed in the hold of the Airbus A321 that crashed on Oct 31, killing 224 people, but airport authorities are struggling to cope with the backlog of suitcases.
The Russian defence ministry has arranged for luggage to be sent home in wide-bodied Russian-made Ilyushin Il-76 military transport jets owned by the Egyptian government. The first two have arrived in Sharm el-Sheikh and the resort of Hurghada.
But British passengers are relying on Egypt Air to return their bags to the UK. With the airport's storage facility full, tourists are being told to leave their luggage in their hotels.
Nasser Hanna, 45, manager of one of the companies handling the Russian flights, said: "Where is Sharm airport supposed to keep all that luggage? It is an airport, not a baggage store."
EasyJet said the first batch of luggage from Egypt was expected to reach passengers by courier by the end of yesterday. Easyjet, Monarch, Thomson and Thomas Cook have extended the cancellation of their flights to Sharm el-Sheikh until Nov 25. British Airways has cancelled all flights until Nov 23.
An Egyptian Civil Aviation Ministry source said: "The Russians and British are the only ones who want no luggage on board. The rest are operating normally. We respect their decision but they have to understand the situation."
More than 7,100 Britons have been brought home. There has been anger that Russian tourists have "queue-jumped", with 4,800 leaving Sharm el-Sheikh every day. But British diplomats in Egypt said that with far more Russians taking holidays in the resort, there were far more Russian flights scheduled to leave anyway.
The pace of repatriation should remain steady for the rest of the week, David Cameron's spokesman said.