Sunni Muslims in Iraq's Anbar province vowed angrily to avenge the death of a tribal leader who led an American-sponsored uprising against al-Qaeda, as they carried his remains to a cemetery in Ramadi today.

Sheikh Abdul Sittar Bezea al-Rishawi, who helped the US military drive the terror group from large swathes of western Iraq, was killed along with three bodyguards yesterday afternoon when his armoured vehicle was torn apart in a bomb attack.

Sheikh Sittar, also known as Abu Risha, met President Bush on a visit to Anbar two weeks ago and had been praised by General David Petraeus, the top US commander in Iraq, for having helped transform one of Iraq's most dangerous provinces into one of its safest.

Thousands of people joined the sheikh's funeral procession as the 36-year-old's body was carried the 10 km (six miles) from his home to a Ramadi cemetery for burial beside his father and brother, both victims of Iraq's sectarian conflict. Two other brothers have been kidnapped and disappeared in the past three years.

“Revenge, revenge on al-Qaeda,” shouted the crowd of mourners, an AFP correspondent reported. “There is no God but Allah and al-Qaeda is his enemy."

Sheikh Sittar's assassination - seen as a heavy blow to Washington - came on the first day of the holy month of Ramadan and almost a year after he formed the Anbar Awakening Conference, a coalition of 42 Sunni tribes who along with US troops fought Al-Qaeda in Anbar.

“We blame al-Qaeda and we are going to continue our fight and avenge his death,” said Sheikh Ahmed al-Rishawi, another of the sheikh's brothers who was elected to lead the tribal coalition.

Nouri al-Maliki, the Iraqi prime minister, was represented at the funeral by his national security adviser, Muwaffaq al-Rubaie, who condemned the assassination. “It is a national Iraqi disaster. What Ab Risha did for Iraq, no single man has done in the country's history,” Mr Rubaie told the mourners gathered at the sheikh’s house. “We will support Anbar much more than before. Abu Risha is a national hero."

In a statement issued by his Baghdad office, Mr al-Maliki said the attack bore “the fingerprints of al-Qaeda” and was “aimed at destabilising the province of Anbar”. The radical Shia cleric Moqtada al-Sadr also condemned the Sunni sheikh’s murder.

“Abu Risha was a man who proved that terrorism can be fought and security can be restored even in the most volatile area in Iraq,” said Sheikh Saleh al-Obeidi, al-Sadr’s spokesman in the holy city of Najaf.

Tareq al-Dulaimi. the Anbar security chief, gave a new version of the attack that killed the sheikh. He said a suicide bomber had blown up his car as Abu Risha’s convoy passed, and that it was not a roadside bomb that killed him as he had initially reported.

“There is reconstruction work going on between the sheikh’s home on one side and a series of orchards on the other so the road which is usually sealed off had to be opened for traffic,” Mr al-Dulaimi said. “The terrorists exploited this situation to drive through a Mercedes car and blow it up near the sheikh’s vehicle."

The interior ministry’s director of operations, Major General Abdel Karim Khalaf, confused issues, however, by saying that in fact two bombs had exploded, the second a car bomb.

Statements on Islamist websites usually used by insurgent groups rejoiced at the sheikh’s killing and said it was the work of al-Qaeda. “The apostate Abdul Sittar al-Rishawi, one of the biggest pigs of the Christian crusade, has been killed by the lions of Islamic unity. This is the beginning of the end of the Anbar Awakening Conference,” one message said.

“Abu Risha wanted to drive al-Qaeda out of Anbar. But al-Qaeda drove him not just from Anbar, but from the world itself."

The sheikh’s killing is seen as a setback to US efforts to contain the violence raging through Iraq and to crush the local wing of Osama bin Laden’s jihadist group. The slow restoration of order in Anbar has been presented as a sign that the US troops surge strategy was working.

In a speech from the Oval Office last night in which he promised a limited troop reduction from Iraq by next July, Mr Bush praised the sheikh's bravery and pointed to the improved security in Anbar as evidence of that U.S. strategy was making headway.

The President said that some 21,500 combat troops would be withdrawn by mid-2008, but ruled out a full withdrawal and promised an “enduring” US presence in Iraq.

“Some say the gains we are making in Iraq come too late,” Mr Bush said. “They are mistaken. It is never too late to deal a blow to al-Qaeda. It is never too late to advance freedom. And it is never too late to support our troops in a fight they can win."

In other developments, the former Soviet republic of Georgia today confirmed plans to cut the size of its military force in Iraq from 2,000 servicemen to 300 by the end of next summer. David Kezerashvili, the Georgian Defence Minister, said that the cut had always been planned and did not reflect a change in policy.

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