Demonstrators had gathered outside the Turkish-operated base in the northwestern Duhok region in anger over the deaths of four civilians last week, which they blamed on Turkish bombardment in the area.

Ankara often carries out air strikes in northern Iraq against the Kurdistan Workers Party (PKK), seen as a "terrorist" group by Turkey, the United States, and the European Union.

Witnesses said several people were wounded when Turkish soldiers fired on the protesters in an effort to push them away from the base in the Sheladzeh district.

The Kurdish regional government said it was "saddened" by the casualties and material damage, but its statement only referred to an "incident" without mentioning Turkey or the protest.

And Turkey's defence ministry said one of its bases was attacked after "provocation by a PKK terror group," resulting in some damage to vehicles and other equipment.

Footage distributed by activists appeared to show protesters setting Turkish military vehicles on fire.

The PKK has waged an insurgency against the Turkish state since 1984, but also operates bases in the Qandil mountain area of Iraq's autonomous Kurdish region.

In addition to air strikes, Turkey has sometimes carried out cross-border operations against the group.

In December, Baghdad summoned the Turkish ambassador to Iraq to protest Ankara's "repeated" air strikes as a "violation of its sovereignty."

Turkey has pressed Iraq to play a bigger role in fighting off the PKK, and last month announced deeper bilateral cooperation on the matter.

Earlier Saturday, Turkey resumed flights between Istanbul and the Iraqi Kurdish city of Sulaimaniyah after a 16-month ban in retaliation for Iraqi Kurdistan's 2017 independence referendum.