Hundreds of mourners turned out to bury an assassinated provincial governor and chief of police on Sunday as the Iraqi prime minister ordered an investigation into their killings, which he called "a seditious act", and appealed for talks to end an ongoing cabinet crisis.

Khalil Jalil Hamza, the governor, and Khalid Hassan, the police chief, of the southern province of Qadisiya were killed by a roadside bomb on Saturday as they headed back to Diwaniya, the provincial capital, from the funeral of a tribal sheikh.

Iraqi police and soldiers tightly surrounded the centre of the Shia city of Najaf, where the bodies were brought on Sunday for burial.

Carrying Iraqi flags and posters of Grand Ayatollah Ali al-Sistani, the country's Shia cleric, the mourners set out from the Shia Supreme Islamic Iraqi Council (SIIC) offices joined by a number of officials.

Police said on Sunday they had arrested two men, a commander of a force that protects infrastructure in Diwaniya, and his deputy, who were believed to have been near the site of the attack.

Investigation ordered

In Baghdad, the office of Nuri al-Maliki, Iraq's prime minister, mourned the passing of Hamza and Hassan and announced that an investigation into their deaths was under way.

Jalal Talabani, Iraq's president, had described the attack as a "cowardly terrorist act" by Sunnis fighters who had been displaced by the current security crackdown by Iraqi and US forces.

Talabani's office said: "They have committed a crime in a secure part of our country after they were besieged and kicked out of Anbar, Diyala and Samarra."

General David Petraeus, the US military commander, and Ryan Crocker, the US ambassador, issued a joint statement condemning the killings.

All-out war?

But Diwaniya residents said on Sunday they feared all-out war among rival Shia factions after Saturday''s assassinations.

The SIIC and supporters of Muqtada al-Sadr, the anti-American Shia leader, are said by local residents to be targeting each other in an armed conflict mainly through assassinations.

SIIC's armed wing, the Badr Organisation, controls the police who fight al-Sadr's al-Mahdi Army militia.

The Shia-dominated south has become increasingly restless as factions vie for control of the oil-rich region, often pitting police loyal to one bloc against militiamen of others.

US Soldiers killed

On Sunday, the US military announced the deaths of five soldiers, four of them in a single explosion, during combat operations in the south of Baghdad.

The soldiers died on Saturday.

Four other soldiers were wounded in the explosion but no other details of the incident were immediately available.

In a separate statement, the US military said a fifth soldier had been killed by small arms fire while on foot patrol southeast of Baghdad on Saturday.

Crisis summit

Also on Sunday, al-Maliki said a much-anticipated summit to try to end political deadlock among the country's leader could begin in the next two days.

The politicians at the meeting are expected to include al-Maliki; Talabani; Tareq al-Hashemi, the Sunni Arab vice-president; Massoud Barzani the Kurdish regional leader; and Abul Aziz al-Hakim, the SIIC leader.

Al-Maliki, whose national unity government has been in crisis since the main Sunni Arab bloc pulled out, said he would either lure it back or find other Sunni Arabs to replace it.

He said: "The first meeting may happen tomorrow or the day after tomorrow."

Nearly half of the cabinet is no longer participating in its meetings.

Besides the Sunni Arabs, supporters of al-Sadr also quit the government, while the secularist bloc of Iyad Allawi, the former interim prime minister, is boycotting cabinet meetings.

Politician's warning

But the head of the Iraqi Accordance Front issued a desperate appeal on Sunday for Arab states to help stop what he called an "unprecedented genocide campaign" by Shia militias armed, trained and controlled by Iran.

Adnan al-Dulaimi said "Persians" and "Safawis", Sunni terms for Iranian Shia, were on the brink of total control in Baghdad and soon would be threatening other Sunni Arab governments.

"It is a war that has started in Baghdad and they will not stop there but will expand it to all Arab lands," he said in an email to AP news agency.

PHOTO CAPTION

US soldiers patrol a street in the restive city of Baquba in the Diyala province, northeast of Baghdad, June 2007. (AFP)

Al-Jazeera