Three members of the counterterrorism forces of Iraq's autonomous Kurdish region were killed and three wounded in Monday's drone strike on Arbat airfield, southeast of the region's second city of Sulaimaniyah.

Around 5 pm (1400 GMT) Monday, "the drone entered Iraqi airspace, crossing the border from Turkey, and bombarded the Arbat airfield," which is mainly used by crop-spraying aircraft, said General Yehya Rassoul, spokesman of the federal armed forces commander in chief.

"This attack constitutes a violation of Iraq's sovereignty", he said, adding: "Iraq reserves the right to put a stop to these violations."

Turkey has stepped up its drone strikes on Kurdish targets in both Iraq and Syria in recent months, although deaths among the Iraqi Kurdish security forces remain rare.

"These repeated attacks are incompatible with the principle of good neighbourliness between states. They threaten to undermine Iraq's efforts to build positive and balanced political, economic and security relations with its neighbours," Rassoul said.

Turkish military action has principally targeted the Kurdistan Worker's Party (PKK) and its Syrian Kurdish ally, the People's Defence Units (YPG).

A Turkish drone strike on Sunday killed a senior PKK official and three fighters in the Sinjar Mountains of northwestern Iraq, Iraqi Kurdish authorities said.

The United Nations mission in Iraq condemned the attack on Arbat airfield.

"Attacks repeatedly violating Iraqi sovereignty must stop," it said. "Security concerns must be addressed through dialogue and diplomacy -- not strikes."

The Turkish army rarely comments on its strikes in Iraq but routinely conducts military operations against PKK rear-bases in autonomous Kurdistan as well as in Sinjar district.

The PKK has been waging a deadly insurgency against the Turkish state for four decades and the conflict has repeatedly spilt across the border into northern Iraq.

Turkey operates dozens of military posts in northern Iraq under an agreement originally struck with the government of executed dictator Saddam Hussein.

In April, Baghdad accused Ankara of carrying out a "bombardment" near Sulaimaniyah airport while US soldiers and the commander of the Syrian Democratic Forces, a US-backed alliance dominated by the YPG, were present.