( AP ) - Shiite cleric Muqtada al-Sadr threatened Tuesday to lift a seven-month freeze on his militia if the Iraqi government does not halt attacks on his followers or set a timetable for a U.S. withdrawal.
The Mahdi Army cease-fire is seen as a major factor in the reduction of violence in Iraq. It has come under severe strain in recent weeks as the Iraqi government has taken on Shiite fighters.
Al-Sadr called off a mass march planned for Baghdad on Wednesday - the fifth anniversary of the U.S. capture of the capital - after hundreds of his followers in areas south of Baghdad complained that Iraqi security forces were keeping them away.
Despite the decision to call off the march, the Baghdad military command clamped a vehicle ban on the capital, saying unauthorized cars, trucks and motorcycles would not be allowed on the streets from 5 a.m. to midnight on Wednesday. The announcement was broadcast on Iraqi state TV.
In Washington, the U.S. general commanding the war called for an open-ended suspension of U.S. troop withdrawals this summer, reflecting concern about a recent flare-up in violence. Gen. David Petraeus left open the possibility that few, if any, additional troops will be brought home before President Bush leaves office in January.
He did not commit to any additional troop withdrawals beyond July.
Petraeus said the recent flare-up of violence in Basra, Baghdad and elsewhere underscored the importance of al-Sadr's cease-fire, which was first imposed for six months in late August and then extended for another six-months. He said the fighting also highlighted the role Iran allegedly plays in funding and training Shiite militias through cells the U.S. military calls "special groups."
"Unchecked, the special groups pose the greatest long-term threat to the viability of a democratic Iraq," Petraeus said.
At least 12 people, including three children, were killed and 37 others were wounded in the fourth day of fighting in Baghdad, hospital officials said, declining to be identified because they weren't authorized to release the information.
"If the public interest dictates the lifting of the freeze to achieve our goals, beliefs, religion, principles and patriotism we shall do that later," al-Sadr said.
Military spokesman Brig. Gen. Qassim al-Moussawi said a total of 82 militants, 36 civilians and 37 soldiers had been killed since March 16 in fighting in Baghdad, mostly in Sadr City, a sprawling area that houses nearly half of Baghdad's population.
The U.S. military later said that three airstrikes had hit mortar launching sites in northeastern Baghdad, killing 12 suspected gunmen in the predominantly Shiite area, which has seen fierce clashes between militia fighters and U.S.-Iraqi forces in recent days.
Iraqi police said 15 people, including women and children, also were wounded in one strike.
But military spokesman Lt. Col. Steve Stover said all three strikes were precise and video footage showed no children or other apparent civilians in the areas.
Rockets or mortar shells also slammed into the U.S.-protected Green Zone, which has faced frequent shelling in the recent unrest. The American Embassy said no casualties were reported.
Al-Sadr faces an ultimatum by Prime Minister Nouri al-Maliki to either disband his Mahdi Army or give up politics. Sadrist lawmaker Hassan al-Rubaie said that because the demonstration has been canceled the government should lift its siege on Sadr City and Shula, another Mahdi Army stronghold in Baghdad.
Using typical rhetoric to refer to U.S. forces, al-Sadr said the government should "protect the Iraqi people from the booby traps and American militias" and "demand the withdrawal of the occupier or a schedule for its withdrawal from our holy land."
Al-Sadr also called on followers to postpone what he had dubbed a "million-strong" march, accusing the government of trying to prevent it.
"I call on the beloved Iraqi people who want to demonstrate against the occupation to postpone their outing for I fear for them and I want to spare their blood," he said in the statement.
The failure of Iraqi troops to crush the militias during the operation that was personally overseen by al-Maliki has embarrassed the government and raised fresh doubts about the ability of the Iraqis to take over their own security so U.S.-led forces can go home.
A U.S. soldier died Tuesday from wounds received in a roadside explosion the night before in northeast Baghdad, raising to 11 the number of American troop deaths since Sunday.
Elsewhere, Iraqi police said a roadside bomb struck a minibus near Balad Ruz, northeast of Baghdad, killing at least six morning commuters and wounding 10 others.
Gunmen also attacked the home of a U.S.-allied Sunni tribal leader near Baqouba, 50 miles north of Baghdad, killing him and three of his sons, police said.
Sunnis who have turned against al-Qaida in Iraq have been frequently targeted since they helped reduce violence in their areas.