ISTANBUL (Reuters) - Turkish police launched raids across the country on Friday, detaining 21 people, most suspected of belonging to Islamic State, the state-run Anadolu news agency reported.
Three of the detainees were foreigners, and authorities believe they were planning to enter Syria to fight for the hardline militant group, which is battling both President Bashar al-Assad's forces and opposition groups backed by Turkey's Western allies.
Under pressure from NATO members, Turkey has stepped up efforts to prevent foreign fighters crossing into neighboring Syria to join Islamic State, which has declared an Islamic caliphate in territory it controls in Iraq and Syria.
The raids come just days after U.S. officials including Retired General John Allen held talks in Ankara on joint efforts to fight the Islamic militants. Washington has been pressing Turkey to do more in the fight against Islamic State.
Brett McGurk, the U.S. deputy special presidential envoy to the anti-Islamic State alliance, on Twitter described the police action as "important raids" against suspected Islamic State agents and facilitators.
Officials at the counter-terrorism department in Istanbul's police headquarters declined to comment.
Authorities seized hunting rifles and ammunition in the simultaneous dawn operations in Istanbul and the nearby town of Kocaeli, as well as in Sanliurfa and Mersin, which are in southern Turkey near the Syrian border, Anadolu said.
Turkey has been a reluctant partner in the coalition against Islamic State, arguing that Assad also needs to be forced from power and fearing territorial gains by Kurdish militias will fuel separatist sentiment among its own Kurds.
In a separate operation targeting the outlawed Kurdistan Workers Party (PKK), police in Istanbul on Friday detained 32 people, Hurriyet newspaper said on its website. The PKK has waged a 30-year insurgency against Turkey but violence has largely stopped since it declared a ceasefire in 2013.
Police seized homemade explosives and nine firearms in the raids, the daily said.
Turkey has watched with concern as Syrian Kurdish PYD forces, backed by U.S.-led air strikes, have pushed back Islamic State militants from Syrian towns near the Turkish border.
Prime Minister Ahmet Davutoglu has said the Syrian conflict poses a major threat to Turkey. Thousands of foreigners have been barred from entering because of security concerns.
Reporting by Ayla Jean Yackley and David Dolan; Editing by Nick Tattersall and Ralph Boulton