Turkey has not been given crucial data to help identify Daesh militants who fled their former stronghold in Raqqa last month under the deal with the U.S.-backed Syrian Democratic Forces (SDF) and may have slipped out of Syria to threaten Turkish or Western targets, Turkish officials said.

Hundreds of Daesh members, including most notorious leaders, and their families were allowed to leave Raqqa by a deal with Daesh and the SDF, predominantly led by PKK's Syrian offshoot People's Protection Units (YPG), who captured the city in mid-October, spokesmen for the fighters and the U.S.-led alliance which supports them said.

The coalition fighting Daesh in Syria and Iraq said last month that biometric information including fingerprints was taken from the militants before their convoy left Raqqa, so they would be known "if they resurface in the future".

But two senior Turkish security officials told Reuters they had not seen any such data which would identify fighters from Raqqa among the hundreds of Daesh suspects rounded up in security sweeps in Turkish cities over the last two weeks.

"If the United States or the coalition received information about Daesh members who were withdrawn from Raqqa and is not sharing it with Turkey, how will we fight against terrorism together?" one official said.

"We didn't receive any biometric data in this office," another security official said.

A third government official said he believed the biometric data had not been shared with Turkey.

Ankara has bitterly criticized the deal to allow militants to leave Raqqa, saying it suspects some fighters have been smuggled across Syria's northern border into Turkey and could pose an international threat.

"These Daesh members, released with their weapons, will cause deaths of innocent people in Europe, the United States, all over the world, especially in Turkey," Prime Minister Binali Yildirim said last week.

His comments reflect long-running tensions with Washington over its support for the YPG terrorists.