The bombing targeted the district of Khwarkuk along the border with Turkey, PKK spokesman Ahmed Danis told AFP.

"The bombing started at around 8:00 pm (1700 GMT) and is still on," he said.

Turkish warplanes have targeted PKK positions in northern Iraq since mid-December. In February, the army conducted a week-long ground offensive against PKK hideouts in the region, where Ankara estimates more than 2,000 militants take refuge.

The Turkish government has a one-year parliamentary authorisation, which expires in October, for raids across the border.

The United States has backed Turkish military action against the rebels by providing real-time intelligence on PKK movements.

The PKK, listed as a terrorist group by Turkey and much of the international community, has been fighting for self-rule in Turkey's mainly Kurdish southeast since 1984. The conflict has claimed more than 37,000 lives.