Turkish authorities on Thursday released three French nationals after they were briefly detained in the Kurdish-majority southeast over alleged ties to outlawed Kurdish militants, a judicial source told AFP.

Security forces had earlier detained 16 suspects in an operation launched in the Beytussebap district of Sirnak province bordering Iraq to capture supporters of the Kurdistan Workers' Party (PKK) and its urban wing the KCK, the source said.

There were no further details on the identity of the freed foreign citizens, with the official Anadolu news agency reporting that one of them was a woman.

The authorities are still battling the over three-decade insurgency of the PKK which initially took up arms for a separate state but now demands a degree of autonomy.

The clashes between Turkish security forces and PKK members have resumed after a fragile ceasefire collapsed in 2015.

The PKK is designated as a terror group by Turkey and its Western allies including the United States and the European Union.