The number of girls and women travelling from the UK to Syria is on the rise after new figures revealed 56 are thought to have fled to the war-torn country last year.
Counter-terrorism officers said they were "deeply concerned" about the number of cases as many women were unaware that they will probably never be able to return home.
Figures released in July showed 43 females were thought to have fled from the UK to Syria in the previous 12 months.
In latest figures, 56 girls and women reported missing by their families between January 1 2015 and December 31 2015 are "all feared to have travelled to Syria", police said.
The figures were disclosed as a short film was released featuring three female Syrian refugees talking about the realities of life in their home country. The women have also written open letters urging British mothers to take steps to prevent their daughters travelling to the war-zone.
Deputy Assistant Commissioner Helen Ball said: "We are deeply concerned about the numbers of girls, young women and also families who are taking the decision to go to Syria, unaware of the dangers they face when they arrive and the fact that they are unlikely to ever be able to return home to their devastated wider families.
"The personal accounts of the women in this film highlight the harsh reality of life for women and children living in a war torn country. I hope they will go some way to helping young women and mothers stop and think about the huge mistake they would be making if they travel."
Recent high profile cases have included school friends Shamima Begum and Amira Abase, both 15, and Kadiza Sultana, 16, all from Bethnal Green, east London, who left for Syria in February. Some are now thought to be married to Isis extremists.
Assistant Chief Constable Angela Williams said: "It is important for everyone do everything they can to help stop people from travelling to Syria and other conflict zones.
"Children have been taken to dangerous places and are at great risk; vulnerable people have been brainwashed into travelling.
"My message to mothers across the region is to please come forward if you have any concerns about your loved ones who may be considering travel to Syria."