The bombardment on Friday caused an explosion near the airport wall while the commander of the Kurdish-led and US-allied Syrian Democratic Forces (SDF) was present. US troops were also in the area but there were no casualties, the Pentagon said.

Around 400 protesters, many of them middle-aged, walked in the centre of Sulaimaniyah, the second city in Iraq's autonomous Kurdistan region.

They waved the flag of Iraqi Kurdistan and held a banner denouncing the airport bombardment as a "terrorist act".

Organised by activists and former parliamentarians, the demonstrators also shouted against the "dictator" President Recep Tayyip Erdogan of Turkey, according to an AFP correspondent.

"This is not the first Turkish aggression against civilian targets in the region," said Ali Amine, 66, a retired civil servant.

"It has become a permanent attack. Sometimes it's villages, sometimes civilian targets -- agricultural land, water or electricity installations."

Another protester, Fatma Hamid, 55, denounced "the lax positions" of authorities in the region which has been autonomous for three decades.

Turkey has long maintained military positions inside northern Iraq, where it regularly launches operations against Turkish Kurdish fighters from the Kurdistan Workers' Party (PKK).

The PKK, which Ankara and its Western allies classify as a "terrorist" organisation, operates rear bases in Iraq's north.

Since 1984 the PKK has waged an insurgency in Turkey that has claimed tens of thousands of lives.

Turkey regards the main component of the SDF, the People's Protection Units (YPG), as an offshoot of the PKK.

On April 3, Ankara halted flights to and from Sulaimaniyah until at least July 3, blaming increased PKK activity in and around the airport.

A source at the Turkish defence ministry denied any involvement by the country's military in the bombardment of Sulaimaniyah airport.

Iraqi President Abdel Latif Rashid on Saturday condemned Turkey's "military operations against the Kurdistan region, the last being the bombardment against Sulaimaniyah civilian airport".