"We are doing what is necessary and we will do what is necessary. Turkey's position is open and clear," he said, in a statement quoted by Anatolia news agency.

Defence Minister Vecdi Gonul, also quoted by Anatolia, said that the US-led coalition had respected its promise not to allow local Kurdish forces to take the city alone, but only under US command.

"The coalition has kept its promises. I think it will continue to do so," he said.

An AFP reporter on the outskirts of Kirkuk said witnesses had told him that US-backed Kurdish forces had taken possession of the city centre without a fight on Thursday.

"The Iraqis withdrew this morning, the population rose up, then the Kurdish fighters arrived," resident Bavi Yassin said.

Turkey has threatened to intervene militarily in northern Iraq if local Kurds are allowed to seize the oil-rich cities of Mosul and Kirkuk.

Ankara fears that control of local oil resources could embolden Iraqi Kurds to move towards independence, a prospect that could set an example to their restless fellow Kurds across the border in Turkey.

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