Baghdad, Iraq ? An explosion damaged part of the main pipeline running from Iraq’s northern oil fields on Thursday, forcing a reduction in the amount of oil available for export.

In Irbil, 200 miles north of Baghdad, police shot and killed the driver of a car packed with 220 pounds of explosives as he approached the police ministry office, the U.S. military said.

The vehicle did not explode, U.S. officials said. Irbil residents contacted by telephone from Mosul said the driver carried an Iraqi identification card issued in Baghdad and giving his age as 19. Last month a car bombing in Irbil killed three people and injured four American intelligence officers.

It was unclear whether the pipeline explosion near the city of Hadeetha, 125 miles northwest of Baghdad, was caused by saboteurs, a senior Oil Ministry official said on condition of anonymity.

He said the explosion ripped open part of the main pipeline linking the northern oil fields to the al-Doura oil refinery and the Mussayab power plant. The oil in the pipeline was earmarked for domestic use.

To maintain domestic supplies, the official said exports from the southern oil fields would be reduced by 80,000 barrels a day to make up for the shortage from the northern oil fields.

There have been many attacks on pipelines in the region, complicating the American rebuilding effort in Iraq, which depends on oil revenue.

L. Paul Bremer, the U.S. civilian administrator for Iraq, has said the country was losing $7 million daily because of the closure of the export pipeline to Turkey. In September, the line reopened for three days for the first time after the war. Three bomb blasts along the line forced its closure.

Iraq is exporting an average of 1 million barrels of oil a day, all of it coming from the southern oil fields.

Also on Thursday, a bomb blast hit a police station in the northern city of Kirkuk, wounding a policeman, Iran’s official news agency IRNA reported. Station chief Lt. Col. Anwar Qader Ahmad said the attackers were Saddam Hussein loyalists.

In Tikrit, meanwhile, a 4-year-old Iraqi girl was killed Thursday when a bomb exploded just outside the main U.S. Army base. Her 12-year-old sister was critically wounded, U.S. officials said.

U.S. officials said they believed the bomb was intended for two U.S. Bradley armored vehicles that had passed down the same road minutes before the blast.