Turkish police have carried out raids in Istanbul and three other cities, detaining at least 21 people suspected of being members of the Islamic State of Iraq and the Levant group (ISIL), state-run news agency has said.
The Anadolu Agency said that three of the suspects detained in the simultaneous raids on Friday were foreign nationals who were planning to cross into Syria to join ISIL.
Their nationalities were not disclosed.
Other suspects were believed to have been working to recruit fighters for the group, the agency said.
The raid comes just days after US officials including Retired General John Allen held talks in Ankara on joint efforts to fight ISIL.
Washington has been pressing Turkey to do more in the fight against the group.
Brett McGurk, the US deputy special presidential envoy to the anti-ISIL alliance, on Twitter described the police action as "important raids" against suspected ISIL agents and facilitators.
Officials at the counter-terrorism department in Istanbul's police headquarters declined to comment.
Anadolu said police seized two rifles, large amounts of ammunition, documents and military uniforms during the raids.
Under pressure from its allies, Turkey has recently tightened security along its border with Syria in a bid to thwart suspected fighters from crossing into the country to join the group.