Aide to Shiite Militia Leader Killed in Iraq

Ambush Could Intensify Clashes Between Sadr's Mahdi Army, Government Troops

BAGHDAD, April 11 -- A senior aide to anti-American cleric Moqtada al-Sadr was assassinated in the holy city of Najaf on Friday, raising fears that the incident could worsen clashes between Sadr's followers and government troops.

The killing of Shiite cleric Riyadh al-Nouri prompted Iraqi officials to declare a curfew in Najaf and send thousands of security personnel into the streets to maintain order. Sadr directed his loyalists to refrain from retaliatory violence.

The assassination threatened to increase tensions between Sadr's Mahdi Army militia and U.S.-backed Iraqi forces, which launched a major offensive against the militia and other groups in the southern city of Basra last month. The fighting had appeared to subside in recent days, but U.S.-led coalition airstrikes Thursday night killed six people in both Basra and the Sadr City neighborhood in Baghdad, the U.S. military said.

Nouri, the head of the Sadr office in Najaf, was shot in front of his house by two gunmen driving a Toyota about 3 p.m. as he returned from Friday prayers in the nearby city of Kufa, according to Col. Ali Nomas Jerao, a spokesman for Iraqi security forces in Najaf.

"The occupier has a hand in this crime in one way or another," Sadr said in statements released by his aides. "I pledge before God and before the people that I won't forget this precious blood. The occupier won't feel happiness in our land as long as I'm alive."

Maj. Brad Leighton, a U.S. military spokesman, said the American-led coalition had no involvement in the assassination. "It's a ridiculous, bogus allegation," he said.

In an interview, Nouri's brother-in-law, Mahdi al-Ghurabi, said his family believed that the Islamic Dawa party, led by Prime Minister Nouri al-Maliki, and the Islamic Supreme Council of Iraq, the largest Shiite party in Iraq and a rival of the Sadrist movement, bore responsibility for the killing.

"They prepared this operation because they knew very well that the assassination of al-Nouri is a heart-rending hit in the heart of Moqtada al-Sadr," Ghurabi said.

Maliki's office condemned the assassination and said it would open investigations.

Gen. David H. Petraeus, the top U.S. commander in Iraq, told reporters during a visit to Washington that the killing was a "cause for significant concern" and said that "it is everyone's interest to maintain the peace in the holy city of Najaf."

Hadi al-Amari, the head of the Badr Organization, the armed wing of the Supreme Council, speculated that the killing was intended to exacerbate tensions between his party and the Sadrists. He praised Nouri as a "dear friend" who had worked to improve ties between the groups.

Nouri, a 35-year-old father of four, was a key figure in the Sadrist movement whose sister is married to Sadr's brother, according to Salah al-Obaidi, the chief spokesman for Sadr.