The Turkish military carried out an airstrike on Sunday on northern Iraqi Kurdistan in the latest operation against Kurdish PKK rebels sheltering in the remote area, a PKK spokesman said.

At least one Turkish warplane hit an area in Iraq's Qandil mountains late on Sunday morning, but there was no confirmation of casualties, PKK spokesman Dozdar Hamo told Reuters.

Turkish authorities did not immediately confirm the operation. The European Union and the United States, as well as Turkey, regard the PKK as a terrorist organisation.

Turkey's military has launched air strikes and limited ground missions into northern Iraq since August this year after a surge in separatist attacks by the PKK, or Kurdistan Workers Party, following the breakdown of an earlier cease-fire.

The PKK launches attacks from hideouts inside the remote Iraqi mountains as part of their fight for more Kurdish autonomy and rights. More than 40,000 people have been killed since the PKK took up arms in 1984.

The PKK in a statement on Sunday also claimed responsibility for hijacking a ferry near Istanbul. It said one of its fighters carried out the hijacking to get the attention of public opinion. It said he had been unarmed.

Turkish commandos on Saturday killed a lone hijacker authorities said was armed with bomb, to rescue more than 20 passengers and crew held hostage for 12 hours on the ferry.

Turkish leaders last month vowed revenge with air and ground strikes after the PKK carried out one of its deadliest attacks in the conflict, killing 24 Turkish soldiers in raids on military outposts in the south of the country.

(Reporting by Shamal Aqrawi; Writing by Patrick Markey; Editing by Michael Roddy)