Ahmed Banz, a spokesman for the PKK, said Turkish artillery fired into the Qalirach area, north of Irbil, which lies close to Iraq's northern border with Turkey.
However, a border guard official in the area said he was not aware of any shelling.
Previous raids
The Turkish army has launched five air raids on PKK targets in northern Iraq as well as a cross-border land operation since December 16.
Ankara says the military campaign is intended to stop PKK fighters from entering Turkey.
The PKK, which is considered a terrorist group by Turkey and the US, has fought a campaign for self-rule in southeast Turkey since 1984.
The conflict has led to the deaths of more than 37,000 people.
Ankara says about 4,000 PKK fighters are hiding in the mountains of northern Iraq, using the camps as bases for attacks inside Turkey.
Thursday's apparent operation comes eight days after General James Cartwright, vice chairman of the US Joint Chiefs of Staff, discussed joint military efforts against the PKK.

Washington has been supplying Turkey, a Nato ally, with intelligence on the separatist group's movements in northern Iraq.
Ali Babacan, Turkey's foreign minister, was quoted by CNN Turk, a private broadcaster, on Tuesday as saying that "the option of a ground operation [against PKK positions in northern Iraq] is on the table".