"No country should resort to unilateral action. Unfortunately this has not been observed," Zebari told AFP, noting that a tripartite security commission -- established to tackle Ankara's concerns -- involving Iraq, Turkey and the United States, had been sidestepped.

Turkish ground forces pushed 10 kilometres (six miles) into northern Iraq on Sunday, killing four people, as they hit back against hideouts of Kurdish rebels who killed 12 of its soldiers.

The ground incursion -- only the second into Iraq in more than two years -- came after Turkish Prime Minister Recep Tayyip Erdogan vowed to fight the Kurdistan Workers Party (PKK), who are demanding self-rule, "to the end."

Zebari, who is himself a Kurd, noted that Turkish air attacks had been going on for months and were "definitely a violation of Iraqi independence, sovereignty and good neighbourly relations."

"I personally believe the reason they are escalating these attacks now is to test the will of the Iraqi government, and also the American forces, as a prelude to the withdrawal of US combat forces in August," Zebari said.

"We are capable of filling the vacuum and we will not allow any other countries to step in to fill that vacuum."

Zebari stressed that Baghdad's relations with Ankara remained guided by "mutual respect," adding: "We do not condone or support any cross-border terrorist attacks by the PKK but, really (Turkey's air attacks) are not the way to handle this problem."

Inside Turkey, the PKK kept up their attacks on Saturday night, killing one soldier and wounding another, bringing the military's losses over the weekend to 12 dead, Turkey's Anatolia news agency reported.

To great fanfare late last year, Erdogan announced a new policy of opening up to Turkey's large Kurdish minority.

But the initiative has faltered amid an opposition outcry that Ankara is bowing to the PKK, as well as persistent rebel attacks and a judicial onslaught on Kurdish activists.

Zebari, however, said the policy must be honoured.

"This initiative is a wise one and needs to be embraced, enhanced and translated into action as the best solution for this age-old problem," the foreign minister said.