At least 20,000 Britons were stranded in Egypt last night as the airline terror crisis escalated.
Downing Street said a bomb smuggled through Sharm El Sheikh airport was probably behind the downing of a Russian airliner at the weekend.
And an emergency review by UK aviation experts has exposed serious loopholes in security procedures at the Red Sea resort.
The Prime Minister is the first world leader to say the Russian Airbus was downed by a bomb.
But hours earlier Islamic State issued a video boasting of shooting down the plane and warning of more attacks.
The crash, which cost 224 lives, would be the first successful airline attack by terrorists since two Russian jets were hit by Islamist extremists in 2004.
The terror alert has left 20,000 British tourists without a flight home. And it throws the travel plans of thousands more into chaos because around 900,000 Britons fly to the Red Sea every year.