"I call on Jaafari to take a courageous step and set a fine example by stepping down," Kasim Daoud, a senior member of the independent group within the Alliance, told Reuters.

Other senior Alliance officials, speaking anonymously, confirmed that four of seven main groups within the bloc wanted Jaafari to give up the nomination for a second term if, as is all but certain, he fails to persuade minority Sunni and Kurdish parties to drop their refusal to serve in a cabinet under him.

"There is a broad trend inside the Alliance who want Jaafari to do this (step aside) and we expect him to do so," Daoud said.

"We have stood behind him for 50 days and today we have reached the conclusion that there should be a prime minister for all Iraqis, not just one group," he added.

"Daoud's call is supported by at least 60 percent of Alliance members of parliament," another senior Alliance official from another group within the bloc told Reuters.

"We need another 24 hours before starting the battle" to pressure Jaafari into resigning, he added.

Alliance officials said the seven key groups inside the bloc had met on Thursday and Friday and concluded by a four to three majority to give Jaafari just days to persuade the Kurds, Sunnis and secular leaders to drop their opposition to him.

That seems highly improbable but a committee of three Alliance officials was holding meetings with the Kurds and Sunnis today. A Kurdish political source said: "Our position regarding Jaafari is clear and has not changed."

The minority groups had formally written this week to Alliance leader Abdul Aziz al-Hakim urging him to produce a more acceptable candidate. Jaafari beat a candidate from Hakim's SCIRI party by a single vote in an internal ballot in February.

It was not clear what mechanism might be used to choose a new nominee for prime minister nor who that might be. A favorite may be the defeated SCIRI candidate, Vice President Adel Abdul Mahdi.

Jaafari continued to have the support of his own Dawa party, its Dawa-Iraq allies and the movement of Iranian-backed cleric and militia leader Moqtada al-Sadr. SCIRI and its Badr allies, the independents and the Fadhila party were against Jaafari.

US diplomats deny accounts from SCIRI and other Alliance officials that Washington has pressured Hakim to drop Jaafari.

However, a US diplomat said on Saturday that it was Washington's analysis that any prime minister must be both competent and able to unite Iraqis -- and that Jaafari did not score well on those criteria. The United States, however, had no preferred candidate in mind and would not impose its views.

In fresh violence, gunmen attacked a minibus carrying Shias northeast of Baghdad, killing six men and wounding one woman, an official said yesterday.

The Shias were returning home from visiting relatives when they were ambushed Friday night near Balad Ruz, about 70km northeast of Baghdad, according to the town's mayor, Mohammed Maarouf.

The motive for the attack was unclear. However, it occurred in a religiously mixed province, which has recorded numerous acts of violence by Shia and Sunni Arab extremists against members of the rival communities.

Tension between the rival Shia and Sunni Muslim communities escalated following the Feb. 22 bombing of a Shia shrine in Samarra and reprisal attacks on Sunni mosques in Baghdad, Basra and other mixed cities.

In other violence, gunmen killed at least six people in the capital, including three ice cream vendors in the southern neighbourhood of Dora and a butcher and his son in east Baghad, police said. Another son was also wounded in the attack on the butcher shop.

In the western Iskan neighbourhood, gunmen killed the owner of an air conditioner repair shop on his way to work. A woman and her child were wounded when a mortar shell landed on their house in central Baghdad, and a roadside bomb targeted a police patrol in the east, wounding two policemen and three civilians, police said.

Police discovered two more bodies of young men shot in the head and wearing handcuffs in Baghdad the latest victims, apparently, of sectarian death squads. Witnesses also told police they saw three gunmen in a BMW pull a handcuffed man out of the car and shoot him near a highway in west Baghdad.

West of Baghdad, US and Iraqi troops killed three suspected insurgents, including a woman, and captured three others in an operation in Amiriyah in Anbar province, the US military said.

In Basra, Iraq's second-largest city, a joint British-Iraqi force detained 14 people, including a policeman, in a dawn raid in two neighbourhoods, Brig. Patrick Marion said. Four detainees were later released, Marion said.

US officials have been pressing the Iraqis to form a government of national unity capable of winning the trust of all communities and cooling the violence. Iraqi political leaders were to meet again Saturday to discuss how much power the prime minister should wield over security forces in the next government.

On Friday, US Ambassador Zalmay Khalilzad urged the Iraqis to speed up the talks. The election was held Dec. 15 and still no government has been formed.

"The terrorists are seeking to provoke sectarian war, and Iraq needs a government of national unity in the face of this threat," Khalilzad told a meeting of Iraqi women. "This government needs to have a good program to govern from the centre, and needs good ministers who are competent.

"Iraq is bleeding while they are moving at a very slow pace," he said.