April 5 (Bloomberg) -- Moqtada al-Sadr, an Iraqi Shiite cleric who incited widespread protests and attacks against U.S. and allied forces yesterday, is the subject of an arrest warrant, U.S. spokesman Dan Senor said in a Baghdad briefing.

The warrant, which has yet to be served, is for the death by stabbing and shooting of cleric Abdul Majid al-Khoei last April at a mosque in the holy city of Najaf, Senor said. An Iraqi investigative judge issued the warrant ``in the last several months'' and Senor said it would now be enforced.

Senor and U.S. Army Brigadier General Mark Kimmitt, the deputy operations chief in Iraq, wouldn't answer reporters' questions concerning when al-Sadr would be arrested, or his whereabouts. ``There will be no advance warning,'' Senor said in the televised briefing.

``The desire of those who don't want a free Iraq is to test our will,'' President George W. Bush said today. ``We've got to stay the course, and we will stay the course.''

As preparations wrapped up for the trial of 13 suspects already in custody in connection with the cleric's murder, the Iraqi judge ``thought he would take another shot at trying to gather up other individuals,'' Senor said when asked why the warrant wasn't used earlier. Al-Sadr's situation ``sort of bubbled up,'' he told reporters.

Followers of al-Sadr, 31, rioted yesterday in Baghdad and Najaf, killing more than 40 Iraqi civilians and at least eight U.S. soldiers. Today, a mob occupied the governor's office in the southern city of Basra.

Concerns

The immediate effect of the unrest was to raise questions among American lawmakers about the wisdom of handing over legal power to Iraqis on June 30. Bush said today that transfer would go ahead. A United Nations envoy is in Iraq to determine the best way to form an interim government that would take power.

The ranking members of the Senate Foreign Relations Committee, Senators Richard Lugar and Joseph Biden, said they were worried the June 30 deadline wasn't feasible and expressed concern about security.

``We're going to end up with a civil war in Iraq if, in fact, we decide we can turn this over'' in a matter of months, Biden of Delaware, said on the ``Fox News Sunday'' program.

It may take as long as three years to get Iraqi security forces trained and ready, he said. Democratic Senator Edward Kennedy, a backer of Senator John Kerry for the presidency, said today that Bush weakened the terror war and Iraq would be Bush's ``Vietnam.''

One Marine was killed today in fighting in Anbar province, part of the so-called Sunni triangle where resistance to the U.S.- led occupation is strongest.

``The arrest and trial are about justice and law and order in Iraq,'' Kimmitt said about the al-Sadr warrant. ``The Iraqi people want elections, not mob violence, to determine who will govern Iraq.''

Fallujah

Fallujah, an Anbar town where American contractors were killed and their bodies burned last week, is now surrounded by about 1,300 U.S. soldiers and Iraqi security forces in Operation Vigilant Resolve. A curfew of 7 p.m. to 6 a.m. is in effect, and traffic checkpoints have been set up, Kimmitt said.

The operation follows last week's killing of four U.S. guards under contract to the coalition. Their bodies were mutilated, dragged through the streets, burned and displayed, and photos of the carnage were published on front pages of newspapers around the world.

U.S. Army General John Abizaid, head of Persian Gulf military operations, has asked his subordinates to research ``options'' on more soldiers for Iraq, CNN reported today, citing unidentified senior Pentagon officials.

Al-Sadr's father, Ayatollah Mohammed Sadr, was assassinated in 1999 by the regime of ousted dictator Saddam Hussein. The son has criticized the U.S.-led occupation of Iraq, and in June formed a militia called the Mahdi Army, the New York Times reported. He doesn't speak with Grand Ayatollah Ali Sistani, the country's leading Shiite cleric.

The Baghdad slum from which al-Sadr draws support was named Sadr City to honor Moqtada's father, Grand Ayatollah Mohammad Sadeq al-Sadr, who was killed in 1999 in Najaf by Saddam's loyalists. The area was known as Saddam City before the war.