A large Sunni Arab group endorsed the Shiite prime minister's national reconciliation plan Tuesday, and his deputy met secretly with exiled Sunni leaders in Jordan to try to win their support and quell the insurgency.

The moves came a day after bombs killed at least 40 people at markets in two cities and key lawmakers said seven Sunni insurgent groups offered the government a conditional truce.

In new violence, a suicide car bomb also struck a busy gas station in the northern city of Kirkuk, killing three people and wounding 17, police Col. Adel Abdullah said.

CountryWatch: Iraq

A parked car bomb exploded in a market in a Shiite section of the dangerous Dora neighborhood in Baghdad, killing at least three people and wounding 10.

A U.S. Marine and a soldier were killed in separate attacks west and south of Baghdad, while another U.S. soldier died Monday in the volatile Anbar province, the military said. That raised to 2,528 the number of U.S. military service members who have died since the war began in 2003, according to an Associated Press count.

U.S. military spokesman Maj. Gen. William Caldwell said an Iraq-led operation launched nearly two weeks ago to restore security to Baghdad was moving slower than hoped.

"It's going to take some time. We do not see an upward trend," he said. "We ... see a slight decrease but not of the degree we would like to see at this point."

In a boost for Prime Minister Nouri al-Maliki's reconciliation proposal, prominent cleric Ahmed Abdul Ghafour al-Samaraie offered the support of his Sunni Endowment, the state agency responsible for Sunni mosques and shrines.

But he urged the government to give details of the plan and said it should include disbanding armed militias, as well as releasing all prisoners who have not been convicted.

"We bless this initiative," he said. "We see a glimpse of hope out of this plan, but at the same time we are noticing that some people are pushing the armed groups to attack some areas in Baghdad, spreading terror and chaos in the city in order to make this plan a failure."

"Thus, the government is required to take decisive actions so that the citizens feel that the state is a real protector," he added. "We think that the first step to be taken regarding this plan is to disband armed militias because the government will not be able to impose the law on everybody with the presence of those militiamen that consider themselves above the law."

Minority Sunnis have accused Shiite-led militias of random detention and torture.

Officials also said Deputy Prime Minister Salam Zikam Ali al-Zubaie met secretly in Jordan with exiled Sunni leaders to win their support for al-Maliki's 24-point reconciliation plan.

Al-Zubaie met with several sheiks from volatile Anbar province — an insurgent stronghold — before al-Maliki unveiled the plan Sunday.

The three-day meetings, which ended Saturday, focused on "efforts for reaching national reconciliation and asserted the need that all sides must cooperate to achieve a civil peace, especially in Anbar," said Abdul-Latif Hemayem, one of the participants.

He declined to give details, saying they were in a "preliminary phase."

"Mr. Al-Zubaie was eloquent and had clear ideas on how Anbar, as a very important province in Iraq, should engage in the political process," Hemayem told The Associated Press.

The Justice Ministry, meanwhile, said 453 more detainees were released from U.S. detention centers across Iraq, part of al-Maliki's plan to free 2,500 by the end of June as a goodwill gesture.

In the first tangible measure after al-Maliki's plan was announced, the council of ministers said government employees who had been detained and recently released will be reinstated to their jobs and their service should be considered uninterrupted in consideration of bonuses, promotion and retirement privileges.

The ministers said freed students will be allowed to return to school to take final exams and won't be failed for the 2005-06 academic year despite time missed.

The measures were decided June 21 by the council to pave the way for al-Maliki's initiative, according to a statement. It said the benefits could only be enjoyed once by former detainees and would not apply if somebody is arrested again.

Monday's bombings served as a reminder of the difficulty in establishing security.

The deadliest was a bicycle bombing in Baqouba, a Sunni insurgent stronghold 35 miles northeast of Baghdad, that killed at least 25 and wounded 33, according to Dr. Ahmed Fouad, director of the morgue at Baqouba General Hospital.

Minutes earlier, a blast killed 15 people and wounded 56 in Hillah, a mainly Shiite city 65 miles south of Baghdad, said police Capt. Muthana Khalid.

The seven insurgent organizations who approached the government are mostly made up of former members or backers of Saddam Hussein's government, military or security agencies, and were motivated in part by fear of undue Iranian influence in Iraq, lawmakers said.

If confirmed, their offer would mark an important potential shift and could stand as evidence of a growing divide between Iraq's homegrown Sunni insurgency and the more brutal and ideological fighters of al-Qaida in Iraq, who are believed to be mainly non-Iraqi Islamic militants.

Kurdish lawmaker Mahmoud Othman linked the offer to al-Maliki's reconciliation plan, involving amnesty for militants — except those who had killed Iraqis, were involved in terrorism, or committed crimes against humanity. Al-Maliki's plan was thought to have denied amnesty to any insurgent who had killed American forces, although the wording was vague.

The Mujahedeen Shura Council, the terrorist umbrella organization that includes al-Qaida in Iraq, rejected the reconciliation plan.

Shiite lawmaker Hassan al-Suneid, who first reported the insurgent groups' gesture, said al-Maliki was considering a possible meeting with their leaders or contacts through intermediaries. Al-Suneid is a member of the political bureau of al-Maliki's Dawa Party.

The opening was confirmed by Othman, a close associate of President Jalal Talabani, who met with seven insurgent organizations about two months ago. It was not clear which groups Talabani met with.

Al-Suneid gave the names of six of the seven organizations that approached the government Monday: the 1920 Revolution Brigades, the Mohammed Army, Abtal al-Iraq (Heroes of Iraq), the 9th of April Group, al- Fatah Brigades and the Brigades of the General Command of the Armed Forces.

"I expect that those groups are the same ones that have made contacts with President Talabani, and now they are widening the range of their contacts. Now they are more serious after the announcement of the (reconciliation) plan," al-Suneid told the AP.

Othman was unable to name the groups or say whether they were the same ones Talabani had contacted. But he said they also sought talks with U.S. forces.

A meaningful truce with insurgents would make it much easier for the United States to withdraw troops from Iraq.

In other developments:

• The Iraqi High Tribunal said a trial will begin Aug. 21 for Saddam and six co-defendants for the 1980s Anfal campaign in which an estimated 100,000 Kurds were killed in northern Iraq. Chief prosecutor Jaafar al-Moussawi said the Anfal case would proceed in tandem with Saddam's current trial if needed.

• A university professor was killed in a drive-by shooting in Baghdad's upscale Mansour neighborhood. The Ministry of Higher Education and Scientific Studies also said it will stage a sit-in in all universities on Wednesday to protest kidnappings and violence against its employees.

• Police found the bullet-riddled bodies of five men in two areas of Baghdad.

• Gunmen tried to kill a tribal chief in the southeastern town of Amarah, seriously wounding Sheik Kadim al-Sebahawi and killing his 22-year-old son.