BAGHDAD, Iraq (CNN) -- A key Sunni sheik who united with U.S. forces to fight al Qaeda militants in Iraq was assassinated Thursday by a roadside bomb, officials said.

Sheik Abdul Sattar Abu Reesha speaks to reporters Wednesday in Iraq.

The bomb struck a convoy carrying Sheik Abdul Sattar Abu Reesha and his security detail, a Ramadi police official and an Interior Ministry official said.

At least two of the sheik's bodyguards were killed and five other escorts were wounded in the afternoon attack.

Abu Reesha, 39, was head of the Anbar Salvation Council -- also known as the Anbar Awakening -- a coalition of tribes that has been working with the U.S. military to counter al Qaeda in Sunni-dominated Anbar province.

The council, funded and supported by Iraqi Prime Minister Nuri al-Maliki, was formed last year.

Al-Maliki blamed al Qaeda in Iraq for the killing, but said it would backfire against the insurgent group by further isolating it across the country.

"We are certain that this will only strengthen the resolve of al-Anbar's honorable sons to fight the terrorists and cleanse Iraq of their evil," the prime minister said in a written statement.

The U.S. military and the U.S. Embassy in Iraq also condemned the attack.

"It is with outrage that the United States and Multi-National Force Iraq condemn the assassination" of the sheik, said Lt. Gen. Raymond Odierno, the day-to-day operational commander in Iraq, in a joint statement with U.S. Embassy in Iraq Charge d'Affaires Patricia Butenis.

"Sheik Sattar will be remembered for his commitment to peace and security in Anbar," their statement said. "He had the courage to build unity in the face of ruthless violence.

"Sheik Sattar exemplified the strength of the Iraqi people in the face of terrorism. His work will go on, and his legacy will never be forgotten."

Police said Abu Reesha was killed about a mile from his home, but the deputy head of the Anbar Salvation Council, Sheik Hameed al-Hayyes, said the bomb struck the convoy 50 meters from his home in a heavily secured zone surrounding the house.

Al-Hayyes said Abu Reesha was leaving his home to go to his nearby farm, a daily routine, when he was attacked.

It is unclear if the bomb was remotely detonated or triggered by the convoy. Al-Hayyes said he suspects al Qaeda may be behind the attack, but could not rule out a rival political group.

"This is a big blow to the Anbar Salvation Council and the sons of all Iraqi tribes in al-Anbar and other provinces," al-Hayyes said. "But the council will continue its work and will step up current security measures for its members."

After Abu Reesha's killing, the council went on Iraq's state-run television to announce seven days of mourning.

Interior Ministry spokesman Abdul Kareem Khalaf told al-Iraqia state TV that the minister of interior has ordered a monument to be built in memory of the sheik, in addition to naming a police brigade after him and dispatching that brigade to Anbar to assist the council.

Abu Reesha was one of several Sunni leaders who met with President Bush during the president's surprise visit to Anbar on September 3. In a photograph taken during the six-hour visit, a smiling Bush is seen shaking hands with the sheik. Watch a closer look at the life of Sheik Abdul Sattar Abu Reesha »

Pentagon spokesman Geoff Morrell said that despite the "tragic loss" of the sheik, "he has ignited a movement that will outlive him."

"His death won't stop this movement at all," agreed retired Gen. David Grange, a CNN military analyst.

Grange predicted that the sheik's killing -- most likely by al Qaeda in Iraq -- will backfire and will "mobilize more sheiks" to come out against the insurgent group.

Such attacks could actually be a measure of the success the United States is having in the restive province, Grange said.

Bush has repeatedly cited successful efforts to bring Anbar tribesmen over to the coalition's side in the fight against al Qaeda in Iraq as evidence of U.S. military success. Since the Sunni sheiks began cooperating with the U.S. military, violent attacks have significantly decreased in Anbar, once a hot spot for al Qaeda attacks.

Bush is expected to reiterate Anbar's success in a major address Thursday night.

Abu Reesha was a prime target for al Qaeda militants and other terrorist groups because of his visible alliance with the U.S. coalition.

Abu Reesha was featured in a documentary, "Land of Fire," that aired on Iraqi state-run television in May in which he explained his reasoning for turning against Sunni militants, particularly al Qaeda, in Anbar province.

"The limit was when it (turned) into a sectarian war," Abu Reesha said. "They lead the people to a sectarian war, they kill a Sunni and say he was killed by a Shiite, they kill a Shiite and say he was killed by a Sunni.

"This led to tensions between the two sects."

The rising tensions paved the way for the Anbar Salvation Council, Abu Reesha said, "because there is no way we will let them kill as they like."

Since achieving success in Anbar, the group announced last month it wanted to extend its reach into Baghdad and the government. It proposed a list of candidates to fill six Cabinet positions vacated in July by the country's largest Sunni political bloc.

Speaking in the al-Iraqiya documentary, Abu Reesha said his group was willing to "liberate all the villages near Baghdad ... and if the government asks us to participate in cleansing Baghdad that will be a great honor for us and we will respond to the call." E-mail to a friend

CNN's Jomana Karadsheh and Mohammed Tawfeeq contributed to this report.

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