The United States Wednesday expressed serious concern over reports that mainly Kurdish security forces have abducted minority Arabs and Turkmens in the northern Iraqi city of Kirkuk. The State Department says U.S.-led coalition forces in the area were not involved, and protested the practice.

The State Department says it has received credible information about alleged extra-judicial conduct, including arrests and detention, by security units in Kirkuk and it says U.S. officials have raised very serious concerns about the reports with local authorities.

The remarks here followed a Washington Post report Wednesday that police and security units led by Kurdish political parties have abducted hundreds of minority Arab and Turkmens in the volatile city, and secretly transferred them to prisons in Kurdish-held northern Iraq.

The newspaper quoted what it said was a confidential State Department cable addressed to the White House, Pentagon and U.S. embassy in Baghdad warning about the activity.

The document said the abductions were part of a concerted effort by Kurdish parties to exercise authority in Kirkuk in what was termed an increasingly provocative manner. It further said the actions had greatly exacerbated ethnic tension in Kirkuk, and endangered U.S. credibility.

At a news briefing, State Department Spokesman Sean McCormack declined to discuss specifics of the State Department cable but acknowledged that reporting from the field by U.S. diplomats did outline what he said were serious and credible reports of extra-judicial activity.

Kurdish security forces have been major U.S. allies in the fight against Iraqi insurgents, but Mr. McCormack denied a charge in the newspaper account that the U.S. military had supported the abductions by the Kurdish-led units.

The spokesman said not only were members of the U.S.-led coalition forces not involved in the activity, but that they raised repeated concerns about it to local officials:

"We want to make clear that the United States and coalition forces have at every opportunity made clear, made very clear, our views on the importance of the adherence to the rule of law, the importance of building and supporting institutions that enforce the rule of law, and our strong support for respect for minority rights," he said. "These are all principles that are contained in the TAL and we would expect all Iraqi officials to abide by those principles."

Mr. McCormack's reference was to the Transitional Administrative Law or TAL, which has served as Iraq's interim legal code since the formal end of the U.S-led occupation last year.

The Washington Post said the abductions in the Kirkuk area began more than a year ago and that U.S. military officials had logged 180 cases of such incidents. Arab and Turkmen politicians were said to put the number at more than 600.

The Kurdish governor of Kirkuk province, Abdul Rahman Mustafa, was quoted in the story as denying the reports of abductions, though he also said persons detained in Kirkuk were often transferred to other areas in order to relieve prison overcrowding.

The report puts renewed focus on Kirkuk, a volatile ethnically-mixed city that Kurdish leaders hope to make the capital of an oil-rich autonomous Kurdistan.

The Kurdish population in the city is growing but is short of a majority. During his rule over Iraq, Saddam Hussein drove many Kurds out of Kirkuk and replaced them with Arabs from the south.

Spokesman McCormack said the status of Kirkuk is a matter for Iraqis to resolve among themselves as provided for in the transitional law. He said any tensions or grievances there need to be settled peacefully and that there is no excuse for going outside the rule of law.