Almost 20 teenage girls fled Britain to join ISIS extremists in Syria last year, it has emerged.

The stream of young women covertly leaving their families in the UK to live with the ISIS terrorists is a "growing problem" of "real concern", said Deputy Assistant Commissioner Helen Ball.

The Met's National Coordinator for Counter Terrorism added that police are in talks with the Government about getting "extra resources" to combat the worrying trend.

Ms Ball told BBC: "In the last year, about 22 young women have travelled to Syria. And when I say young, all but four of those 22 were aged 20 or younger.

"The last five who've travelled were aged 15 and 16.

"This is a growing problem and it's one of real concern."

Her comments came after three schoolgirls from East London left their homes and are believed to have travelled to Syria during February half-term.

It is feared Kadiza Sultana, Shamima Begum and Amira Abase fled in a bid to become 'jihadi brides' for ISIS terrorists.

The schoolgirls may have now joined the other 400 British females – many also as young as 15 – already feared to have joined the ISIS, either as frontline fighters or as brides for the terrorists.

Questions have been raised as to whether airlines should do more to prevent young women flying out to Syria.