Turkey often carries out ground and air operations in northern Iraq against positions of the Kurdistan Workers' Party (PKK), which has waged a decades-long insurgency against the Turkish state.

"A Turkish drone struck a civilian car at 3:20 pm (1220 GMT) killing... two women and two men," said a security source in the Raparin area north of the city of Sulaimaniyah.

"Their identities remain unknown," the source added, speaking on condition of anonymity as they were not authorised to speak to the media.

Kamran Othman from the US-based Community Peacemakers Teams (CPT) group monitoring Turkish operations in Iraqi Kurdistan, confirmed the attack took place.

"Two women and two men were killed," said Othman, adding that a fifth person on a nearby motorcycle was wounded.

The PKK, which is listed as a terrorist organisation by Turkey and its Western allies, holds positions in Iraq's Kurdistan region, which also hosts Turkish military bases.

During a visit to Baghdad, Turkish Foreign Minister Hakan Fidan called on Sunday for combined regional efforts to combat the PKK in Iraq, as well as Kurdish fighters in neighbouring Syria, whom Ankara accuses of having links to the outlawed group.

"I want to emphasise this fact in the strongest way: the PKK is targeting Turkey, Iraq and Syria," Fidan said.

Baghdad has recently sharpened its tone against the PKK, and last year it quietly listed the group as a "banned organisation" -- though Ankara demands the Iraqi government do more in the fight against the militant group.

Fidan said his country hoped Baghdad would declare the PKK a "terrorist" organisation.

In August, Baghdad and Ankara signed a military cooperation deal to establish joint command and training centres with the aim of fighting the PKK.