BAGHDAD, Iraq — A Shiite alliance won a slim majority in Iraq's new National Assembly, according to certified election returns announced yesterday, but it may take weeks to form a government.

Because a two-thirds majority in the 275-member parliament is required for confirming the top positions in the new government, the United Iraqi Alliance will have to make deals with the other parties. The alliance won 140 seats, while Kurdish parties got 75, secular Shiites took 40 and nine smaller parties shared 20, the final returns of the Jan. 30 elections showed.

Shiite and Kurdish leaders have agreed that they must reach out to prominent Sunnis to participate in the government if they want it to be considered legitimate among Sunnis and to have any hope of ending the country's largely Sunni-led insurgency.

The Sunni-led Iraqis Party won only five seats in parliament, because many Sunni Arabs avoided the elections — either out of fear of violence or to support a boycott call by radical clerics opposed to the U.S. military.

The key challenge for the new government will be ending the insurgency that kills dozens of people every week. Most Iraqis say only negotiations will end the attacks.

Two U.S. soldiers were killed yesterday in separate attacks in the northern Iraqi city of Mosul, the U.S. military said today. A car bomb exploded next to a U.S. army patrol, killing one soldier and wounding three, the military said. In a second attack, a soldier was shot dead in an exchange of fire with guerrillas.

In Baqouba, 35 miles northeast of Baghdad, Iraqi police killed two men with suspected links to al-Qaida's affiliate in Iraq and arrested five others during raids, the city's police chief, Major Gen. Adel Molan, said yesterday.

"We found huge amounts of weapons, including mortars, assault rifles and explosives. We also found computers and CDs which show the beheading of several hostages in addition to letters which they were about to send to Osama bin Laden," Molan said of Tuesday's raids.

In the latest hostage ordeal, a Swedish citizen kidnapped in Iraq appeared in a video with a gun pointed at his head, appealing to the pope and Sweden's king to help win his release from insurgents, Swedish media reported. A group calling itself "Martyr of al-Isawy Brigades" said it kidnapped the Swede of Iraqi descent as he traveled from Mosul to Baghdad this month.

The National Assembly will be in power for only 10 months, and its main job will be to draft a constitution so new elections can be held in December.

But it won't convene until disputes are resolved over who will become prime minister — the top post in the new government.

The Kurdish parties have apparently agreed to support the alliance's candidate for prime minister in return for the largely ceremonial presidency, though they have also offered to produce a compromise candidate for prime minister, if needed. Kurdish officials have said they would not accept a theocratic government.