Twin teenage girls who are thought to have travelled to Syria are "deeply religious Muslims", police understand.
It is understood an older brother has joined the extremist militant group Islamic State of Iraq and the Levant (Isis), and one line of inquiry is that the girls may have flown out to join him.
The girls, from a large Somalian family, flew from Manchester International Airport to Turkey which borders Syria where the civil war involving Muslim militants is raging.
Greater Manchester Police said the pair had been in contact with relatives since their departure.
More top news
Thirty facts about Prince Harry to celebrate his coming of age.
Django Unchained actress Danièle Watts was handcuffed by police after she was seen "showing affection" to her partner, NBC News reported.
A US news anchor has told viewers he only has four to six months to live on air, after he was informed that his brain tumour was inoperable.