KIRKUK, Iraq (AP) – A suicide attacker detonated a car bomb Saturday outside an Iraqi police academy as hundreds of trainees and civilians were leaving for the day, killing 20 people and wounding 36 others in the latest attack designed to thwart U.S-backed efforts to build a strong Iraqi security force ahead of January elections.

U.S and Iraqi forces, meanwhile, launched an operation in another northern town, Tal Afar, to flush out a militant cell allegedly smuggling men and arms in from Syria, sparking a fierce gunbattle that left at least eight people dead and more than 50 injured.

South of Baghdad, attackers fired mortar rounds at an Iraqi police patrol, killing three officers, said Col. Adnan Abdul-Rahman of the Interior Ministry. The attack occurred between the towns of Mahmoudiya and Latifiyah 25 miles from the capital.

The car bomb in Kirkuk littered the street with bloodied bodies, gutted cars, shards of glass and twisted metal. The police academy’s steps were covered in blood.

“I saw one of my friends killed before my eyes. I couldn’t do anything to help him,” said Bassem Ali, a student at the academy who was hurt in the blast.

Kirkuk police put the toll at 20 dead and 36 wounded.

“This is a terrorist act against members of Iraqi police who were going home,” said Kirkuk police Col. Sarhat Qadir.

No one immediately claimed responsibility for the attack.

Insurgents see police as collaborators with U.S.-led forces and are bent on disrupting American efforts to build a strong Iraqi security force ahead of January elections.

Militants have blown up police stations all over the country, gunned down officers in drive-by shootings and battered police recruitment centers with mortar barrages and rocket-propelled grenades – leaving policemen increasingly terrified and deterring would-be recruits.

From April 2003 to May 2004 alone, 710 Iraqi police were killed out of a total force of 130,000, authorities said.

In Tal Afar, a U.S. OH-58D Kiowa helicopter was hit by enemy fire and forced to make an emergency landing, said U.S. Army Capt. Angela Bowman. The aircraft’s two crew members were wounded, she said.

A U.S. Stryker Brigade vehicle securing the helicopter’s site was later attacked by rocket-propelled grenades, the military said. Troops fought back, killing two attackers.

The attacks came amid fierce resistance to smash a militant cell operating in the town, which U.S. intelligence believed had become a haven for militants crossing the border from Syria.

Fawazi Mohammed, the head of the local hospital, said at least eight people died and another 50 were wounded during the clashes. Many of the casualties were caused by a mortar shell explosion in a Tal Afar market, authorities said.

In Baghdad, mortar rounds landed near a convention center where members of Iraq’s 100-member transitional assembly, known as the Iraqi Council, gathered for a meeting. Despite the explosions, delegates elected four vice chairmen of the National Council, which is intended to act as a watchdog over the interim government of Prime Minister Ayad Allawi until the election.

The Cabinet met Saturday and agreed to allocate more funds to security operations and rebuild areas damaged by fighting. They also decided to build up a strategic food reserve able to supply the country for three months, Allawi’s office said in a statement.

Also Saturday, saboteurs blew up an oil pipeline in southern Iraq, part of a campaign of attacks on the country’s oil infrastructure aimed at hampering reconstruction efforts.

Firefighters struggled to put out the blaze caused by the explosion near Hartha, 19 miles north of Basra, and technicians were forced to shut down the pipeline, said police Maj. Col. Nouri Mohammed.

Its shutdown is not expected to significantly affect Iraqi oil exports.

In the latest hostage crisis, Iraqi militants threatened to behead a Turkish truck driver if his employers and a Kuwaiti contractor don’t leave Iraq within 48 hours, according to a video aired Saturday on the pan-Arab television channel Al-Arabiya.

The group, calling itself the Islamic Resistance Movement-Al-Noaman Brigades, released a tape showing a bearded man, purported to be the truck driver, sitting in front of a black banner bearing the group’s name in gold Arabic characters. It was not immediately possible to verify the tape’s authenticity.

More than 100 foreigners have been kidnapped since the U.S.-led invasion of Iraq in March.

France’s foreign minister, Michel Barnier, returned home from the Middle East without winning the release of two French journalists held hostage since mid-August. But Interior Minister Dominique de Villepin said in Paris that there were signs Christian Chesnot and Georges Malbrunot could be released soon.