By Andrew Gray
Baghdad - A sea of mourners filled northern Baghdad on Sunday to bid farewell to a top Shi'a Muslim cleric killed in a bombing, as officials said up to five Iraqis had been detained over the attack.
The governor of the holy city of Najaf, scene of Friday's bombing in which 83 people were killed and 175 were wounded, said the suspects had links to the old power structure of ousted President Saddam Hussein.
"There are several suspects, none of whom has citizenship other than Iraqi," Haidar al-Mayyali told a news conference.
Asked about reports the attackers had links to Osama bin Laden's al-Qaeda network, Mayyali said: "There is no exact information on this matter."
The attack intensified international debate on stabilising Iraq, with Russia saying it would back a United Nations force for the country - even if it was under United States command.
In a sign the diplomatic pace may be quickening, US President George Bush, Italian Prime Minister Silvio Berlusconi and Russian President Vladimir Putin held phone talks on Iraq on Sunday.
Crying men and women dressed in black thronged streets around Baghdad's golden-domed Mousa al-Kadhim mosque for the start of the funeral rites of Ayatollah Mohammed Baqer al-Hakim, who advocated cautious co-operation with Washington.
The tens of thousands of mourners chanted and beat their chests in traditional Shi'a rituals as the coffin draped in a large black cloth was carried through the crowd to a truck, guarded by men with automatic rifles.
Hakim, who returned to Iraq from 23 years of exile in Iran after US-led forces toppled Saddam in April, headed the Supreme Council for the Islamic Revolution in Iraq (SCIRI), one of the country's most prominent Shi'a groups.
His killing sent shockwaves through Iraq's Shi'ites, who make up around 60 percent of the 26 million population.
The funeral procession will take in several Shi'a holy sites in Iraq before a burial ceremony on Tuesday in Najaf, 160km south of Baghdad.
Many Shi'as have blamed Friday's attack on die-hard supporters of Saddam, who repressed the Shi'ites when he was in power. Some analysts have suggested Shi'as opposed to Hakim's moderate political position could be to blame.
The slain cleric's brother Abdul Aziz al-Hakim, who sits on Iraq's US-appointed Governing Council that Washington sees as a first step towards democratic elections, said US-led forces bore some responsibility as security was in their hands.
"They are ultimately responsible for the innocent blood which is being shed every day... all over Iraq," he said.
Mohammed Bahr al-Uloum, a leading Shi'a scholar, said he was suspending his membership of the Governing Council in protest at Hakim's killing.
Iraq's US-led interim administration says it faces a tough balancing act as it wants to provide security but not offend Muslims by placing foreign troops near holy sites.
US officials have said little about who they think was behind the bombing, but have cited foreign Islamic militants as possible suspects for similar attacks earlier this month which targeted the UN offices and the Jordanian embassy in Baghdad.
Authorities said two booby-trapped cars had exploded in the attack and around 700kg of explosives had been used.
Hakim's nephew Ammar al-Hakim said: "According to the limited results of the investigation... up to now we can say that the (Saddam) regime in cooperation with certain extremists was behind this. They could have extensions beyond Iraq."
Washington has blamed daily and often deadly raids on its troops and other targets mainly on Saddam loyalists, but has made increasing mention of al-Qaeda and other foreign fighters.
Since Bush declared major combat over on May 1, 65 US and 11 British soldiers have been killed by hostile fire and the US-led administration in Baghdad has been plagued by sabotage to the country's protentially lucrative oil industry.
The US military said on Sunday US forces killed six Iraqis who attacked their convoy with rocket-propelled grenades and small arms fire. Two US soldiers were wounded in the incident on Saturday just west of the northern city of Kirkuk.
The United Nations said it had moved expatriate staff in the southern city of Basra to Kuwait due to security concerns, but they would return on a daily basis to carry out their work.
Some diplomats argue there would be less hostility towards a a UN-sponsored and more multinational force than the current US-dominated one of around 150 000 soldiers.
Washington has recently appeared more open to a possible UN force, as long as it has the command, and major powers have been discussing the possibility of a new UN resolution to encourage more nations to send troops to Iraq.