BAGHDAD, Iraq, May 26 — American troops killed a "very large number" of rebels during fighting in urban Shiite areas today and captured a lieutenant of the radical cleric who has led a movement resisting occupation forces for more than a month, American officials said.
The battles since early April between militias loyal to the cleric, Moktada al-Sadr, and American-led occupation forces have complicated preparations for the handover of sovereignty to Iraqis on June 30, including the formation of a caretaker government.
An Iraqi nuclear scientist, Hussain al-Shahristani, has been identified as the leading candidate for prime minister in the period leading up to January 2005 elections, but Iraqi and American officials said today that there were others under consideration.
Fierce fighting erupted early today in the cemetery area of the Shiite holy city of Najaf, south of Baghdad, residents said. Local medics said up to 26 Iraqis were killed and more than 30 were injured. They did not specify if the casualties were rebel or civilian.
The American forces also captured a lieutenant to Mr. Sadr, Said Riyad al-Nouri, Mr. Sadr's brother-in-law.
He was handed over to Iraqi authorities for prosecution in connection with the April 2003 murder of a rival of Mr. Sadr.
In the Sadr City neighborhood in Baghdad, rebels using rocket-propelled grenades and small arms fought with American troops, and an American military spokesman, Brig. Gen. Mark Kimmitt said "a very large number" of rebels were killed in both places.
"We are constantly chipping away at his militia," said General Kimmitt at a news briefing in Baghdad, referring to the fighters who say they are allied behind Mr. Sadr.
"We are continuing to chip away at his militia that is there in Najaf, as we saw from operations that we held last night."
He offered no specific casualty figures, telling reporters later that "less than 100" fighters died. There were no reported deaths among coalition troops in the Najaf and Sadr City fighting.
In other violence today, two Russian technicians were killed and at least five others were wounded when their convoy was hit by rebel gunfire, news services said.
The technicians were employees of the Russian company Interenergoservis, which said today it would evacuate all its remaining staff from Iraq. The firm's workers have been abducted and killed in previous attacks.
Russian engineers have specialized in maintaining Iraq's fragile electrical system.
In Baqubah, militants driving a black Opel attacked the Al-Khalis chief of police with small-arms fire, killing both the chief and his driver, General Kimmitt said.
In southwest Baghdad, a roadside bomb was detonated, killing three Iraqis and wounding nine, the general said. Two suspects were killed in the explosion and one was wounded, he said, adding that two Iraqi police officers were also wounded in the blast.
The developments came a day after the the Shrine of Imam Ali, one of the holiest sites for Shiite Muslims, suffered minor damage in clashes between American forces and insurgents loyal to Mr. Sadr in Najaf and in the neighboring city of Kufa.
"We just can't tell you how much we decry the attempts by Moktada's militia, Moktada possibly himself, to violate the sacred holy shrines of the Shia religion for his own personal gain, for his own personal advancement," General Kimmitt said Tuesday.
Aides to Mr. Sadr said on Tuesday that American fire had damaged the shrine. And before the shrine was damaged, an aide to Mr. Sadr, Hosam Mosawi, strongly criticized the deaths in the two cities and raised the concern that the shrines would become targets for American soldiers.
The fighting, both with the Shiite militia and Sunni insurgents linked to the former Iraq government, has shown little sign of abating as the June 30 deadline for the handover of authority to Iraqi authorities looms.
A United Nations envoy, Lakhdar Brahimi, is expected to announce the lineup of the caretaker government next week.
"The report that there is actually a candidate nailed down is incorrect," the Coalition Provisional Authority's senior adviser, Dan Senor, said at a news briefing in Baghdad.
The Iraqi Governing Council president, Sheikh Ghazi Mashal Ajil Yawir, told reporters today that there were several candidates. "The debate is still going on," he said.
Christine Hauser reported from Baghdad for this article and Kirk Semple reported from New York.