BAGHDAD, Iraq (CNN) -- Violence raged for a fourth straight day in Baghdad's Sadr City, leaving 20 more Iraqis dead on Wednesday.
At least seven people were killed and 38 others wounded in a mortar attack and gunfire, an Iraqi Interior Ministry official said. Six people died in clashes between U.S. and Iraqi forces and members of the Mehdi Army, the militia of radical Shiite cleric Muqtada al-Sadr.
Five people were killed and 14 others were wounded when attackers fired at a tent of mourners for a person killed in this week's fighting.
An unmanned aerial vehicle killed two "armed criminals" attacking security forces, the U.S. military said.
The International Zone, the seat of U.S. power in Baghdad known as the Green Zone, was hit again Wednesday by rockets or mortars, the U.S. Embassy said. There were no reported injuries. The U.S. military said Shiite militants backed by Iran have been staging such attacks.
Wednesday's violence falls on the fifth anniversary of the fall of Baghdad. It also comes as the two top American officials in Iraq, commanding Gen. David Petraeus and Ryan Crocker, U.S. ambassador to Iraq, testify before U.S. congressional committees about the status of the war. They said Tuesday that Iranian agents and weapons are fueling the ongoing strife there and that further U.S. troop withdrawals will have to wait.
Clashes in Sadr City, a Shiite enclave in the capital, has killed 67 Iraqis and wounded 243 since Sunday, and nine U.S. troops have died in Baghdad during the same period.
The Sadr City fighting reflects the intra-Shiite power struggle in Iraq between Iraqi security forces dominated by the Islamic Supreme Council of Iraq and al-Sadr's Mehdi Army militia.
The upsurge in violence between Iraqi security forces and the Mehdi Army started with a March 25 government offensive in parts of the Shiite city of Basra in southern Iraq. It targeted what the government calls criminal elements.
Al-Sadr suspended the activities of the Mehdi Army last August, a truce that U.S. military commanders have cited as a major reason for a decline in violence across Iraq.
Earlier this week, Iraqi Prime Minister Nuri al-Maliki demanded that al-Sadr disband the Mehdi Army or see his supporters -- who hold seats in Iraq's parliament and once backed the prime minister's ruling coalition -- barred from public office.
Iraqi President Jalal Talabani on Wednesday backed al-Maliki's call.
"We have high hopes that they will respond to the call from all political powers to dissolve the Mehdi Army and work as a respectable trend with their role in parliament and the political process," Talabani said at a news conference.
Al-Sadr on Tuesday raised the possibility of formally calling off the cease-fire.
The Sadrist movement helped put al-Maliki in power and holds 30 seats in Iraq's 275-member parliament. But it bolted from the prime minister's ruling coalition, the United Iraqi Alliance, last year when al-Maliki wouldn't set a timeline for the withdrawal of U.S. troops. The alliance includes al-Maliki's Dawa Party and the Islamic Supreme Council of Iraq.
Al-Sadr initially urged a massive demonstration Wednesday in the capital against the U.S. presence in Iraq to coincide with the anniversary of Baghdad's fall. But he called off the protest, accusing al-Maliki's government of trying to suppress the event "under American pressure."
"I call on the beloved Iraqi people who wish to demonstrate against the occupation to postpone this, because I am worried about them and want to preserve their blood," al-Sadr said Tuesday.
A statement from the capital's military operations command said any demonstrations must be held in Sadr City, the cleric's base of support, and that protesters must stay at least 1,600 feet (500 meters) from police or troops. Any violations would be met "firmly and forcefully," the statement said. The Sadrists wanted to demonstrate in a wider area.
• U.S. Special Forces destroyed an al Qaeda in Iraq training camp and a large weapons cache last week in northern Iraq's Jazeera Desert, the American military said Wednesday. Airstrikes helped destroy an old radar station that insurgents were suspected of using. U.S. troops found weapons, including surface-to-air missiles and rockets, mortar rounds and explosives materials, and ammunition, the military said.
• A U.S. soldier died Wednesday in Baghdad from "noncombat-related injuries," and a roadside bombing killed another soldier Tuesday east of the capital, the U.S. military said. The number of U.S. military deaths in the Iraq war stands at 4,027, including eight Defense Department civilians. There have been 15 troop deaths in April. E-mail to a friend
CNN's Jomana Karadsheh contributed to this report.