"(U.S. Secretary of State Collin) Powell said they would send new U.S. forces to Kirkuk in a few hours. They will take out those who have entered," Gul said.

"We will have military observers there... They (the United States) made the offer and we accepted it," he added.

"We will see in the field whether a fait accompli will be allowed in Kirkuk or not," he stressed.

Gul was speaking hours after Powell assured Ankara that it would send reinforcements to Kirkuk to replace Kurdish forces who seized the city earlier in the day.

Turkish Defense Minister Vecdi Gonul said earlier Thursday U.S. forces had promised that Kurdish fighters would only be allowed to enter Kirkuk under U.S. command, Anatolia news agency reported.

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

"Ankara refuses to envisage the possibility that the United States might not keep its word," Turkish daily newspaper Milliyet commented on Thursday.

Gul assured earlier on Thursday that Turkey will not allow Kurdish refugees to change the demographic make-up of the oil-rich northern Iraqi cities of Mosul and Kirkuk.

"We will not permit either armed people or those without arms, who could try to destroy the demography and the structure of these towns," he threatened.

He was speaking just after Iraqi Kurdish fighters backed by U.S. forces captured Kirkuk.

Ankara fears that if Iraqi Kurds wrest control of Iraqi oil resources they could seek independence, triggering a similar move among the restless fellow Kurds just across the border in southern Turkey.

Fighting between the Turkish army and the country's separatist Kurds claimed more than 36,000 deaths between 1984 and 1999.

Violence has since subsided in southeastern Turkey but Ankara is taking no chances.

Kirkuk is a prized target for the Kurds and has been designated as capital by the Patriotic Union of Kurdistan (PUK) - one of the Kurdish groups controlling the part of Iraq just north and east of Kirkuk and Mosul.

Iraqi Kurds lay claim to Kirkuk and Mosul, saying they were in the majority there before the cities were taken over by Arabs under the regime of Iraqi President Saddam Hussein.

Apart from a brief period when it was captured by the Kurds during the 1991 Gulf war, the city has to date remained under Baghdad's control.

Saddam sought to reduce Kurdish influence in Kirkuk in the late 1970s by settling Arabs there and driving out thousands of its Kurdish residents and the ethnic Turkic minority - the Turkmen, said AFP.

Last week Powell sought to assuage Ankara's concerns, while simultaneously warning against any Turkish intervention in northern Iraq.

"There is no need for any movement of Turkish forces across the border," Powell told a joint news conference with Gul in Ankara.

"We have been able to stabilize the situation in the way that I think will keep the likelihood of a need for an incursion very much under control," he added.

Leaders of Iraq's ethnic Turkish minority - the Turkmen - expressed dismay at the fall to Kurdish forces on Thursday of Kirkuk to which they both have historical claims.

"We are seriously concerned. We fear for the fate of our people living in the city," Ahmet Muratli, the representative of the Iraqi Turkmen Front (ITC) in Turkey told AFP in his office in a posh Ankara neighborhood.

His remarks are testimony to the long-standing unease between the Turkmen and the Kurds in northern Iraq, who have clashed in the past, and who both lust after Kirkuk and its sister town of Mosul.

"We want the United States and Turkey to keep their pledges to us," Muratli said his eyes fixed on a television blaring out reports from the war zone.

Turkmens say they are the third largest ethnic group in northern Iraq after the Arabs and the Kurds, and estimate their own numbers at three million.

"The United States has accepted the ITC as the official representatives of the Turkmen. We have asked them to accept the Turkmen as one the founding peoples along with the Arabs and the Kurds," Muratli said.

Such a move, strongly supported by Turkey, would give Turkmens a say in the administration of a future Iraq.

Kurds, on the other hand, dismiss Turkmen claims, saying their community is no larger than half a million and they consider Kirkuk as their own prospective capital in a federal Iraq.

But sharing out the cities will almost certainly be a difficult task following decades of ethnic tensions.

"We only want our rights back. We want the return of the land which was forcibly taken from us," Muratli said while underlining dislike of seeing Kurdish refugees coming into the cities.

Kurds talk about 300,000 to 400,000 people returning to the cities. "We do not like this. I call on the world not to let the demographic structure of the cities be disrupted," he said.

The only way to determine who has a majority in the cities is to check birth and death records, and the land registry, Muratli said.

The last census was carried out in the 1950s.

"We ask that these records be examined after the war. with Turkey as an observer," he said.