Ordinary Turks were horrified as the latest move by peshmerga fighters, backed by America, was beamed live by CNN Turk. Government officials called it “unacceptable”. Abdullah Gul, the Foreign Minister, asked Colin Powell, his American counterpart, what had become of US promises that Kirkuk would not be handed to Kurdish control.

In a hastily arranged telephone call, General Powell vowed that US forces would ensure that the peshmerga retreated.

Yesterday’s swift promise from General Powell was in line with an “early-warning” system set up by the two countries. It was designed to head off clashes between Turks and Kurds and marks US anxieties that tensions in northern Iraq could yet wreck hopes of a peaceful end to the conflict.

Apparently reassured, Mr Gul emerged to say that earlier US guarantees were valid and that Kirkuk and Mosul, another oil-rich city, would not come under permanent Kurdish control.

“There is no question at the moment of Turkish troops going abroad,” he told reporters. Later he said Washington had confirmed that its troops had entered Kirkuk and were in control. “There is no problem,” Mr Gul said. “As long as they do not allow a fait accompli in Kirkuk or Mosul, everything is fine.” He added, however, that any attempt to change the ethnic make-up of the mixed population of Kurds, Arabs and Turkomans by flooding the city with Kurdish migrants would be a serious concern for Turkey, and could be a trigger for Turkish “intervention”.

The Pentagon confirmed that US special forces had accompanied the initial contingent of Kurds into the city and were later reinforced by elements of the Army’s 173rd Airborne Armoured Brigade.

For Turkey, a Kurdish Kirkuk would presage a Kurdish state stretching across its borders and renewed cries for Kurdish independence in southeast Turkey. There was no sign last night that Turkish troops would defy America, but, massed on the border, they remain an ominous presence.

Mr Gul said that America had agreed to the presence of Turkish military observers in the region, but gave no further details. The deal was outlined last week when General Powell visited Turkey. But it was only yesterday that General Powell agreed to allow Turkey to send a small group of military monitors.

However, Mehmet Dulger, head of the Turkish parliament’s foreign affairs commission, said it was unbelievable. “A terrible picture. We are in a very sensitive situation.”

The Turkish public had a firm view on the events. “Have you heard, the Kurds are in Kirkuk?” a youth in Istanbul said. “Yeah! We should go and zap them,” replied a cakeseller across the road.

Turkish sensitivities are acute when it comes to northern Iraq and, more specifically, the Kurds. The military has barely finished fighting a 15-year insurgency by Turkish Kurd guerrillas in southeast Turkey that claimed more than 30,000 lives on each side.

Many officials believe that the creation of an autonomous Kurdish area after the first Gulf War offered a haven for the rebels. Iraqi Kurds, however, see Kirkuk as theirs, saying that they were systematically expelled by an Iraqi Government that sought to “Arabise” the city.

The Kurdish people

Ethnicity: whereas Arabs are of Semitic origin, the Kurds are descended from Indo-Europeans and speak a language that is Indo-European in origin

Religion: Sunni Muslim

Population: more than 24 million in the Middle East. 13.5 million in Turkey, 4.8 million in Iraq, 5 million in Iran and 300,000 in Syria

Kurds in Iraq Population: nearly five million living mainly in the Kurdish region of Iraq, an area the size of Scotland. Most Iraqi Kurds live in the Kurdistan Autonomous Region, which occupies more than half of the Kurdish area of Iraq. It has been under the control of the Kurdistan regional government since 1991

Political parties: the Patriotic Union of Kurdistan (PUK), towards the eastern border with Iran, whose flags are green, and the Kurdistan Democratic Party (KDP), towards the northern border with Turkey, whose flags are yellow. The two groups signed a unity pact this year

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