BAGHDAD &

Shiite cleric Muqtada al-Sadr threatened today to lift a seven-month freeze on his Mahdi Army militia if the Iraqi government does not halt attacks on his followers or set a timetable for a U.S. withdrawal.




The cease-fire credited with helping bring down violence has been under severe strain since fighting broke out last month in the wake of a government crackdown on militia violence in the southern city of Basra.




The threat to lift the freeze came from al-Sadr's office hours before the top two U.S. officials in Iraq &

Gen. David Petraeus and Ambassador Ryan Crocker &

started briefing Congress on the situation in Iraq and prospects for drawing down American troops.




"I call on the Iraqi government, if it exists, to work for the protection of the Iraqi people, stop the bloodshed and the abuse of its honor," said al-Sadr, who faces an ultimatum by Prime Minister Nouri al-Maliki to either disband his Mahdi Army or give up politics.




"If the public interest dictates the lifting of the freeze to achieve our goals, beliefs, religion, principles and patriotism we shall do that later," he said.




U.S. and Iraqi troops stepped up their pressure on Mahdi Army militiamen in their Baghdad stronghold of Sadr City, where fighting broke out again early today after Iraqi units tried to enter the area, a police officer said.




Explosions could be heard across the capital, apparently coming from the neighborhood in eastern Baghdad. Low-flying jets circled the center of the capital several hours before sunrise.




The two sides were using small arms, rocket-propelled grenades and mortars, said the police officer, who spoke on condition of anonymity because he was not authorized to release the information to the media.




Fifteen civilians were wounded in the clashes, he said.




Petraeus called for an open-ended suspension of U.S. troop withdrawals this summer, asserting that an overly rapid withdrawal would jeopardize security gains.




He told the Senate hearing that he recommends a 45-day "period of consolidation and evaluation" once the extra combat forces that President Bush ordered to Iraq last year have completed their pullout in July. He did not commit to a timetable for resuming troop reductions after the 45-day pause.




"At the end of that period, we will commence a process of assessment to examine the conditions on the ground and, over time, determine when we can make recommendations for further reductions," Petraeus said.




Bush is expected to accept Petraeus' recommendation.




Military spokesman Brig. Gen. Qassim al-Moussawi said 82 militants, 36 civilians and 37 soldiers had been killed since March 16 in fighting in Baghdad, mostly in Sadr City.




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 has extended an order made last year to his Mahdi Army fighters to stand down through August, but he warned he could lift the unilateral cease-fire if the Iraqi government fails to provide the public with security and stability.




Al-Sadr also called off a "million-strong" march planned for Wednesday in Baghdad after followers in Shiite areas south of Baghdad complained that Iraqi security forces prevented them from traveling to the capital.




The demonstration was supposed to mark the 5th anniversary of the capture of Baghdad by invading U.S. forces.




As a deadline for militia fighters to surrender their weapons expired, Interior Ministry spokesman Maj. Gen. Abdul-Karim Khalaf, who was leading continued operations in Basra, said some gunmen had complied but he could not provide a number.




Police in cities elsewhere in southern Iraq said few had surrendered their weapons and they were awaiting orders to resume raids.




Al-Moussawi gave a three-day deadline for gunmen to disarm in Baghdad's northern neighborhood of Kazimiyah, the site of the capital's holiest Shiite shrine complex.




Khalaf also confirmed that 1,000 Iraqi security forces had "failed to carry out their duties" and promised action against them after reports of widespread desertions during a military crackdown in Basra.




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.




A U.S. soldier died today from wounds suffered 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.




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.




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Associated Press Writers Sinan Salaheddin, Bushra Juhi and Hamid Ahmed contributed to this report.