BAGHDAD, Iraq - U.S. troops captured a key lieutenant of radical Shiite leader Muqtada al-Sadr during overnight clashes in Najaf that killed 24 people and wounded nearly 50, hospital and militia officials said.

Riyadh al-Nouri, al-Sadr's brother-in-law, offered no resistance when American troops raided his home during a series of clashes in this Shiite holy city, according to Azhar al-Kinani, a staffer in al-Sadr's office in Najaf.

The capture of al-Nouri would be a major blow to al-Sadr's al-Mahdi Army, which has been battling coalition forces since early April. Al-Sadr launched his uprising in response to a crackdown by coalition authorities who announced an arrest warrant against him in the April 2003 assassination of a moderate cleric in Najaf.

In Baghdad, diplomatic sources confirmed reports published today that Dr. Hussain al-Shahristani, a science adviser to the Iraqi government who spent years in Abu Ghraib prison, was among several people under consideration for the job of prime minister of an interim government to take power June 30. The sources, speaking on condition of anonymity, emphasized that no decision had been made and other candidates were under consideration.

Before the Iraq war, al-Shahristani was among the Iraqi exiles who had insisted that Saddam maintained weapons of mass destruction. In February 2003, he told CBS' "60 Minutes" that such weapons may have been hidden in tunnels for a Baghdad subway that never opened.

Despite his concerns about mass destruction weapons, al-Shahristani said in London in 2002 that he was "extremely concerned of the consequences" of an invasion of Iraq on the Iraqi people.

Also today, masked gunmen opened fire on a convoy taking Russian technicians to work at a Baghdad power station, killing two and wounding at least five, Iraqi and Russian officials said. It was only the latest attack on employees with the Interenergoservis company.

In Moscow, the executive director of the company, Alexander Rybinsky, said today the firm would evacuate all its staff from Iraq. The attacks on the Russians could be an attempt to undermine international efforts to rebuild the country, since Russian expertise has played an important role in reviving Iraq's electricity industry and other infrastructure.

A roadside bomb exploded today on Baghdad's Tahreer Square near a main bridge across the Tigris river, damaging a U.S. Army vehicle. There was no word on casualties.