West Yorkshire Police are "extremely concerned" for the safety of 12 members of a Bradford family who are missing after travelling to Turkey following a pilgrimage to Saudi Arabia.
The Dawood family - three sisters and their nine children - reportedly arrived in Istanbul from Medina on June 9 and have not been heard from since.
The sisters are 30-year-old mother-of-two Khadija Dawood, 34-year-old mother-of-five Sugra Dawood and 33-year-old mother-of-two Zohra Dawood.
The children are aged five between 15. They were due back in the UK on June 11.
Police said their disappearance was reported to them on June 11 and they had been "supporting the family and carrying out extensive enquiries".
A force spokesman said officers were "working extensively with authorities overseas to try and locate them".
Assistant Chief Constable Russ Foster said: "We are extremely concerned for the safety of the family and would urge anyone with information to come forward and speak to us.
"Our priority is for their safe return; their families are gravely worried about them and want them home. One of our primary concerns is the safety and welfare of the young children”
Turkey has been a common route for Britons travelling to Islamic State-controlled territory in Syria and Iraq. There is no evidence the family are heading to Syria.
The BBC's Daniel Sandford said the family would "easily be the largest family group" to have travelled there from the UK if that is what they are doing.
The family's details were released by Khans Solicitors in Bradford, a spokesman for which told local paper The Telegraph And Argus: “The family are extremely concerned as to the whereabouts of the missing persons and their welfare.
"There has been no contact from any of the family since June 9, 2015. The mobile telephones with the group have not been active since June 9, 2015. Their social media profiles have also not been updated since that date.”