David Cameron concerned over Syria-bound London girls
The Prime Minister has said he is "hugely concerned" that four girls feared to want to go to Syria attended the same school as four other pupils who have already travelled there.
All eight are pupils at Bethnal Green Academy in Tower Hamlets.
Three are thought to have gone to Syria via Turkey in February and four were barred from travelling abroad last week.
The school has denied it has a problem with radicalisation.
'Murder and mayhem'
On how worried he was eight girls from the same school seemed to want to travel to the war-torn country, Mr Cameron told BBC London: "I am hugely concerned about this. As is, I think, the whole country.
"That girls from this country have chosen to go out and join a death cult that believes in murder and mayhem and terrorism."
A case in High Court revealed on Friday that four pupils at the school had had their passports confiscated over fears they would try to reach Syria.
In December, Sharmeena Begum, 15, became the first pupil from the school to travel to Syria.
In February, Kadiza Sultana, 16, Shamima Begum, 15, and Amira Abase, 15, followed in her footsteps.
All four teenagers are now thought to be in Raqqa, the Syrian city where Islamic State has its headquarters.
When asked directly what would happen to the girls if they came home, Mr Cameron said: "Whoever has gone out to join a terrorist organisation is breaking the law and has to face the consequences of breaking the law and we have to let the law take its course in the proper way."
The Prime Minister appeared to contradict the Met Police which has previously said the three girls would not be treated as terrorists if they were to return to the UK.
The force said its position has not changed.
Bethnal Green Academy has not responded to requests to comment.