BAGHDAD - Anti-U.S. Shiite cleric Muqtada al-Sadr threatened a new uprising Saturday if U.S. and Iraqi forces persist with a crackdown against his followers.

The statement, which was posted on his Web site, accused the U.S.-backed government of Shiite Prime Minister Nouri al-Maliki of betraying the movement and the Iraqi people.

"So I direct my last warning and speech to the Iraqi government to refrain and to take the path of peace and abandon violence against its people," al-Sadr said in the statement. "If the government does not refrain and leash the militias that have penetrated it, we will announce an open war until liberation."

Al-Sadr fiercely opposes the U.S. presence in Iraq and launched two major uprisings against U.S.-led foreign forces in 2004. His Mahdi Army militia also was accused of being behind some of the worst retaliatory sectarian violence against Sunnis after the February 2006 bombing of a key Shiite shrine in Samarra, north of Baghdad.

The cleric ordered his fighters to stand down in late August. But the truce has been severely strained by crackdowns against his Mahdi Army militia in Baghdad's Sadr City and the southern city of Basra.

"Do you want a third uprising?" al-Sadr asked in the statement.

He also evoked a comparison with Saddam Hussein's Sunni-dominated regime, which widely suppressed Iraq's majority Shiites.

"Despite our freeze of the Mahdi Army, our initiatives to defuse the tension and our calls for peaceful protests and strikes, after all these negotiations and concessions, you are becoming arrogant and adopt the policies of Saddam who used to ban Friday prayers, close the clerics' offices and resort to assassinations," he said.

The lifting of the Sadrist cease-fire could jeopardize recent security gains. The military considers the truce one of the pivotal factors behind a sharp decline in violence, along with a Sunni revolt against al-Qaeda in Iraq and an influx of some 30,000 U.S. troops.

The recent fighting began when al-Maliki launched an operation against Shiite militias in Basra on March 25, prompting widespread retaliation throughout the southern Shiite heartland as well as the main Mahdi Army stronghold of Sadr City.

Al-Maliki, himself a Shiite, also said publicly this month that al-Sadr must disband the Mahdi Army or get out of politics.

The government and the U.S. military have said they are targeting criminal gangs, not al-Sadr's movement. But the cleric and his followers have accused them of trying to undermine the group ahead of expected provincial elections in the fall.