IRBIL, Iraq - U.S. troops backed by attack helicopters and armored vehicles raided an Iranian diplomatic office early yesterday and detained six of the Iranians working inside. It was the second surprise seizure of Iranians by the U.S. military in Iraq in recent weeks and came a day after President Bush had bluntly warned Iran to quit meddling in Iraqi affairs.

The raid provoked a tense standoff later in the day between U.S. soldiers and about 100 Kurdish troops, who surrounded the U.S. armored vehicles for about two hours in this northern Iraqi city.

In Baghdad, meanwhile, police said that at least 45 people were killed or found dead yesterday from bombings and shootings, the Associated Press reported.

The attack in Irbil was denounced by senior Kurdish officials, who are normally Washington's closest allies in Iraq but regarded the action as an affront to their sovereignty. Iran's Foreign Ministry reacted with a harsh denunciation that threatened to escalate tensions with the Bush administration.

The U.S. military said in a statement that it had been "conducting routine security operations in Irbil Jan. 11 and detained six individuals suspected of being closely tied to activities targeting Iraqi and Coalition Forces. One individual was released and five remain in custody."

With U.S. attack helicopters roaring above the normally placid neighborhood here, U.S. troops backed by armored vehicles broke into the office at about 3:30 a.m., carrying away documents and computer equipment.

Black Hawk helicopters also swooped over the confrontation with the Kurdish troops, and at least two landed, an American witness said. There were no reports of shots being fired, and the incident ended peacefully.

Witnesses said the attack was directed at a building that a U.S. official described as a liaison office that was properly accredited with Iraq as an Iranian government facility. It was unclear whether the Iranians who were arrested carried diplomatic passports and whether the office was supposed to share some of the immunities enjoyed by embassies and consulates.

Local residents said the main function of the office was to process travel papers for people seeking to go to Iran for visits or medical treatment.

The Iranian government said the raid violated international law and demanded the detainees' release.

"This is a provocative action by the United States and is against all international laws and regulations," said the Foreign Ministry spokesman, Mohammad Ali Hosseini, state-run radio reported.

A senior State Department official said that the Iranian office in Irbil was not technically a consulate but rather a liaison office that also provided some consular services. He said U.S. officials believed the Iranians intended to turn the office into a consulate at some point, but that had not yet happened. Therefore, he said, the State Department did not consider the office to be Iranian territory.

In late December the U.S. military detained a number of Iranians in Baghdad, including two diplomats and two individuals who turned out to be senior Iranian military officials. The diplomats were released, but the others were forced to leave Iraq under suspicion they had been working with Shiite militias.

GI Gets 18 Years in 3 Iraq Killings

A U.S. soldier was sentenced yesterday to

18 years in prison in the killing of three detainees during a raid last year on a suspected al-Qaeda compound in Iraq.

Spec. William B. Hunsaker, 24, had pleaded guilty to murder, attempted murder and obstruction of justice during a hearing at Fort Campbell, Ky.

As part of a plea agreement, charges that Hunsaker had threatened another soldier's life if he told authorities of the killings were dropped.

Hunsaker, of the 101st Airborne Division, was

one of four soldiers charged in the killings near Samarra, about 60 miles north of Baghdad.

Pfc. Corey R. Clagett, 21, and Staff Sgt. Raymond L. Girouard, 24, are awaiting courts-martial. Spec. Juston R. Graber, 21, pleaded guilty Tuesday to a lesser charge of aggravated

assault as part of a deal to cooperate with prosecutors. Graber was sentenced to nine months in a military jail.

- Associated PressEndText