The official, speaking on condition of anonymity, made his comments shortly after Turkey's Prime Minister Recep Tayyip Erdogan warned Washington his country would decide by itself whether and when to send troops into northern Iraq, an area controlled by Iraqi Kurdish factions.

"Turkey should not go into northern Iraq unless there is sufficient justification and no better way of dealing with it," the official said.

The United States wants to avoid "a war within a war" breaking out in northern Iraq between Kurdish factions and Turkish forces who harbour deep suspicions about each other's motives, he said.

Iraqi Kurds fear Turkey wants to occupy their region for the long term.

Turkey fears the Kurds might declare a separate state, a move which could reignite a secessionist rebellion among its own Kurdish minority just across the border.

Turkey has given a number of reasons for its possible intervention, including dealing with a sudden influx of war refugees or renewed threats from Turkish Kurdish rebels belonging to the Kurdistan Workers' Party (PKK).

Ankara has agreed however not to deploy any additional forces in northern Iraq "in the immediate future" and to do so "only if necessary" and "in coordination" with the United States, the US official said.

The Turkish army has long maintained a military presence of several thousand troops inside Iraq to fight the PKK.

It recently deployed some 50,000 additional troops along the border for a possible large-scale intervention in case the war in Iraq should spawn turmoil in the border region.

Iraqi Kurdish leaders, who recognize that setting up a separate state is "not realistic", have agreed not to try to seize Kirkuk, an oil-rich town currently held by the forces of Saddam Hussein, and not to call for a rebellion of Kurds now living in the city, the US official also said.

He acknowledged that Ankara had expressed concern that local Kurds might take over the city, a move that could boost their claim -- both economically and politically -- to a separate state.

Kurdish fighters have advanced on Kirkuk over the past couple of days as Iraqi forces fell back from their advanced positions around the city.

In an address to parliament on Saturday, Erdogan said Ankara was willing to listen to Washington, its long-time ally, as long as its security interests were not undermined, but hinted that Turkey would act on its own if it perceived a threat.

"We do not want to doubt that our sensitivities would be taken into consideration by our allies, but no one should doubt that we will do what is necessary as an independant and sovereign state if a situation which hurts our sensitivities emerges," he said.

His warning came as Turkish diplomats and US envoy Zalmay Khalilzad, just back from meeting Iraqi Kurdish leaders in northern Iraq, met here to coordinate policies over northern Iraq.

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