NAJAF, Iraq — Followers of the renegade cleric Muqtada al Sadr chanted anti-American slogans and vowed revenge for the assassination Friday of Sadr's top aide in Najaf, where outrage over the killing threatens to spiral into the second deadly uprising in southern Iraq in a month.
Riyadh al Nouri, 41, who ran the main Sadr office in Najaf and was known as a relative moderate within the movement, was gunned down as he returned home from prayers Friday afternoon, according to Iraqi authorities and the Sadr camp. No group has claimed responsibility for the slaying, which amounted to a highly provocative strike at Sadr's inner circle. Nouri was Sadr's brother-in-law.
"Long live Sadr! Muqtada is the bridge to heaven!" mourners chanted at Najaf's sprawling cemetery. Other slogans cursed the U.S. military and its Iraqi allies. Throngs of Sadr supporters referred to Iraqi Prime Minister Nouri al Maliki as "the enemy of God," "infidel," "coward" and an "agent of the Americans."
"The martyrdom of Seyyed Riyadh al Nouri has burned my heart, and I will not rest until I have avenged him," said Mohamed Hassan, a Mahdi Army militiaman who drove from the town of Kufa for the funeral.
The timing of the killing — not even two weeks after more than 120 people died and at least 300 were wounded in fighting between Sadr's militiamen and government forces in the port city of Basra — raises the specter of a wider rebellion that could spread to Sadr's strongholds in Baghdad.
That scenario would only further tax the outgunned Iraqi security forces and could undo the gains of the U.S. military's widely touted troop buildup strategy.
Sadr, who's believed to be studying theology in neighboring Iran, issued a statement blaming the United States and the Iraqi government for his aide's assassination, describing his enemies as acting "traitorously and aggressively against our dear martyr." Sadr also demanded a swift investigation from the authorities and calm from his furious supporters.
"We will not forget this precious blood. I call upon Sadr followers to be patient. The occupiers will not rest in our land as long as I am alive," Sadr said in the statement.
Maliki quickly condemned the killing and said gangs were behind the attack. In a brief televised address, Maliki also mourned Nouri and included the slain Sadr aide among targeted "moderate religious personalities."
Nouri was married to one of Sadr's sisters, and one of Nouri's sisters is married to Sadr's brother, Mustafa, according to the Najaf office. Despite their close relationship, Nouri had at times challenged his militant brother-in-law and was well known for his stance against spilling the blood of Iraqi security forces and rival Shiites, as well as his opposition to the Sadr movement's decision last year to step down from posts in Maliki's administration.
Nouri was also Sadr's handpicked chief negotiator with the Iraqi government, said Abdulhadi al Mohammedawi, director of the Sadr office in nearby Karbala.
Nouri also had his detractors, who recall his arrest by U.S. troops in May 2004 in connection with the brutal killing a year earlier of another Shiite cleric, Sheik Abdul Majid al Khoei, just after the American-led invasion of Iraq. Nouri and a co-defendant were released in 2005 under an agreement to end an early Sadrist uprising that left thousands of Iraqis dead.
The Khoei killing resurfaced Friday as a possible motive in the assassination of Nouri. With no suspects in police custody by late evening, Najaf residents debated whether the killing was a covert U.S. operation to dismantle the Sadr network, or was undertaken by rival Shiite Muslim parties locked in a power struggle with Sadr, or was committed by Sunni extremists, members of the former regime or other tribal, religious and political enemies.
Nouri's death heightens the tensions engulfing the southern Shiite heartland, where Sadr's men are fighting government-allied Shiite rivals for supremacy and turf. On Friday, residents mostly ignored the curfew that the government imposed after the assassination. Motorists drove right through checkpoints, and thousands of mourners marched to fulfill Sadr's call for a fitting burial for his comrade.
The enormous, men-only funeral procession ended at the Sadr family's private plot at the Valley of Peace cemetery, where Nouri was buried according to Islamic custom. Iraqi government snipers looked on from rooftops, and few, if any, state authorities searched or blocked members of the procession. Occasionally, Sadr's supporters hurled pebbles at the state security forces or cursed and threatened them at checkpoints.
(Special correspondent Qassim Zein reported from Najaf; Allam reported from Baghdad. Special correspondent Sahar Issa contributed from Baghdad.)