A homicide car bomber targeted a busload of police recruits north of Baghdad on Monday, killing seven people, and gunmen in the capital killed five workers, police said.

Iraq's Kurdish president met with the Shiite prime minister in northern Iraq for talks on the formation of the country's next government.

At least three police recruits were killed by the car bomb in Baqouba, and another four people also died, although officials couldn't immediately say whether they were recruits or civilians. Thirteen people were wounded, police said. The bus had been traveling to a training center in Baqouba, 35 miles northeast of Baghdad.

In the capital, gunmen in two cars opened fire on laborers, killing five, police Capt. Qasim Hussein said.

Elsewhere, a 7-ton truck slammed into a bus carrying civilian contractors on a U.S. air base in the western Anbar region Sunday, the U.S. military said Monday. Four American civilian contractors were killed, and 18 civilians were injured, including eight who were flown by medical helicopter to Baghdad.

The cause of the accident was under investigation. No hostile action was involved, the military said.

In other violence, gunmen clashed with police in western Baghdad, killing three policemen and wounding two, police Maj. Moussa Abdul Karim said.

A car bomb exploded in Baghdad near an American convoy, Hussein said. Police had no information on casualties, and U.S. officials do not usually comment on such attacks.

A convoy carrying Turkey's ambassador to Iraq was fired on as it sped through western Baghdad, damaging some of vehicles but causing no injuries, the embassy said. AP Television News video showed several of the cars' bulletproof windows had been smashed in by bullets.

Fuel resumed flowing at Iraq's largest oil refinery for the first time in nearly two weeks because of deteriorating security. The shutdown forced stations around the country to ration gas, creating long lines.

"We started (Sunday) to supply the tankers with oil products after the government promised to secure them along the highways," Ahmed Ibrahim Hamadi said Monday.

Oil Minister Ibrahim Bahr al-Uloum said Monday he resigned after the government last week gave him a forced vacation and replaced him with Deputy Prime Minister Ahmad Chalabi following criticisms about sharply increased fuel prices.

Al-Uloum said he resigned because the government raised prices by up to nine times on Dec. 19, a decision he had strongly criticized.

Prime Minister Ibrahim al-Jaafari and the ministers of defense and education were welcomed by President Jalal Talabani, a Kurd, in Sulaimaniyah, 160 miles northeast of Baghdad, on Monday.

Al-Jaafari is a leading member of the United Iraqi Alliance, a religious coalition of majority Shiites that won the most votes in the Dec. 15 parliamentary elections, according to preliminary results.

Sunni Arabs made their opening bid Sunday in what could be protracted negotiations to form a new government. Leaders of the minority's main political group, the Iraqi Accordance Front, traveled to the northern city of Irbil for a Monday meeting with the president of the Kurdish region, Mazoud Barzani.

Barzani met Sunday with al-Jaafari and agreed on "essential principles for exerting efforts to form a broad-based government," Barzani said.

Preliminary results from the elections have given the Shiite group a strong lead in the voting for Iraq's 275-member parliament, but not enough for it to govern without other political blocs. Final results are expected as early as this week.

A year ago, it took nearly three months of negotiations between the Shiite religious alliance and a coalition of Kurdish parties to form an interim government after a Jan. 30 election that was boycotted by the Sunni Arabs at the core of the insurgency.

The first three months of 2006 look more crucial as Iraq tries to shape an administration that will govern for four years. U.S. officials are pushing the parties to form a broad-based coalition government, and failed negotiations could worsen civil strife.

Iraq's main Sunni Arab groups agreed after talks with Barzani that a broad-based coalition government was the only way to end violence in the country. They insisted, however, that contested election results must first be scrutinized by international assessors.

"We pray to God to help all so that this country may get out of this trial and that it regain stability, security and peace is regained again," said Tarek al-Hashimi, head of the Iraqi Islamic Party. "These meetings represent important steps toward in the right direction."

He added that Iraq's political parties had agreed "on one basic principle concerning the type of the coming government, although we are very preoccupied now with the challenges we presented by the results of the Independent Electoral Commission of Iraq."

Adnan al-Dulaimi, the head of their joint Iraqi Accordance Front group, said after the meeting with Barzani that an agreement had been reached in principle.

"The conclusion from all that we heard from the other's opinions is that there is an agreement to form a balanced Iraqi government by consensus and cooperation and away from any sectarian affairs," al-Dulaimi said.

The Irbil meetings came ahead of Monday's visit to Iraq by a team of international monitors who will assess the elections. The United Nations has called the polls credible, but opposition groups have denounced them as rigged.

Al-Hashimi also told the Al-Jazeera television channel that the minority Sunni Arab party Iraqi Accordance Front would not boycott the next parliament — a threat that has been made by smaller groups — and would promote Sunni Arab demands for broad amendments to the constitution approved in an Oct. 15 referendum.

In other violence Monday:

— Police found the bodies of eight civilian men handcuffed, shot and dumped at a sewage plant in southeast Baghdad. The body of a policeman shot in the head was found in western Baghdad.

— Police found three bodies in Iskandariyah, 30 miles south of Baghdad, police Capt. Mothana Khalid said.

— A roadside bomb in Baghdad killed one civilian, said police Capt. Mohammed Abdulghani said.

Thirteen Iraqis were killed in violence Sunday, and 13 car bombs exploded around the country.