BAGHDAD, Iraq (AP) -- Iraq's prime minister urged hundreds of tribal leaders Saturday to join his efforts to end sectarian strife and terrorism, warning that U.S. forces are unlikely to withdraw from the country until Iraqis unite.

"Brothers, the national reconciliation is a wide door, open to all those who want to take part in rebuilding the country," Nouri al-Maliki said at the first of four conferences planned across Iraq by his new national reconciliation committee.

The prime minister set up the panel last month to bridge the deep divisions among the country's Shiite and Sunnis and to bring Sunni Arab insurgents into the political mainstream. His comments touched on the widespread displeasure with the U.S. presence here.

"Liberating the country from any foreign existence and controlling the enemies can't be achieved without a real national unity among Iraqis and this is the role for our tribes," said al-Maliki, a Shiite.

"These tribes have to play a significant role in fighting terrorists, saboteurs and infiltrators," he told the leaders, most of them wearing checkered headscarfs. Others wore suits or loose Kurdish trousers.

"Yes to unity, yes to Iraq," some tribal chiefs chanted between speeches.

"We are all brothers in this country."

The leaders of powerful tribes on Saturday signed a solemn "pact of honor" vowing to halt their country's slide into the chaos of sectarian war, AFP reported.

Amid scenes of celebration at a Baghdad hotel, the chieftains -- who represent clans from across the country and all the major ethnic and religious groups -- promised to support a government-backed peace process.

Reading the charter, Sheikh Faal Namah said he and his colleagues vowed "to preserve our country, stop bloodletting and displacement among Iraqi people and halt the activities of takfiris (violent Sunni insurgents)".

The accord will be seen as a boost for the embattled prime minister.

Iraq's vicious cycle of tit-for-tat sectarian attacks erupted after a Feb. 22 bombing of a Shiite mosque in Samarra. The Shiite-dominated government was already reeling from frequent bomb attacks by Sunni Arab insurgents.

The two-pronged violence killed nearly 10,000 people between May and July. Violence appeared to dip in August, thanks to a major security operation by U.S. and Iraqi forces in Baghdad, where much of the fighting has taken place.

The minority Sunni Arabs held power under Saddam Hussein's regime, which had repressed all other groups — Arab Shiites, the mostly Sunni ethnic Kurds, Chaldean Christians and ethnic Turkomen. "Iraq, at this stage, needs all its sons. There is no difference among Kurds, Arabs and Turkomen, Muslims or Christians, Sunnis or Shiites," al-Maliki said.

"That doesn't mean that we don't have different opinions, but we have to rely on dialogue not weapons."

Akram al-Hakim, the minister for national dialogue, said Iraqi politicians of different backgrounds must make concessions to each other to achieve unity.

"But at the same time, I say that such concessions should not violate our national and constitutional principles," he said.

"The reconciliation cannot be achieved by appeasing one group and discriminating against another."

Reconciliation seems a distant goal as no major Sunni Arab insurgent group has publicly joined the effort. Al-Maliki and his fellow Shiites have said insurgents who have not killed could be given amnesty. But given the widespread bloodshed, it could be hard to find militants who meet that requirement.