Fierce clashes and mortar attacks in Baghdad's Shiite bastion of Sadr City killed 13 people on Wednesday as Iraq marked the fifth anniversary of the overthrow of Saddam Hussein.

Iraqi officials said three mortar rounds slammed into Sadr City, the east Baghdad stronghold of anti-US Shiite cleric Moqtada al-Sadr, killing at least seven people and wounding 24.

One of the three rounds struck the rooftop of a house where a family was having breakfast, killing an adult and two children.

Clashes in the sprawling Shiite district of some two million people in the early hours killed another six people and wounded at least 15, a medic said.

Sadr City has been wracked by renewed fighting between Sadr's Mahdi Army militia and US and Iraqi forces since Sunday. At least 55 people have died and scores more have been wounded.

The US military says it is chasing "criminals" firing rockets into Baghdad and the heavily-fortified Green Zone where the Iraqi government and US embassy are based.

On Wednesday, Baghdad's streets were empty of cars and trucks after the authorities declared a 5:00 am to midnight (0200 GMT to 2100 GMT) vehicle curfew to prevent car bomb attacks by Sunni insurgents.

Saddam's hometown of Tikrit was also under a day-long curfew, an AFP correspondent said.

It took US forces just three weeks to defeat Saddam's forces and topple his regime on April 9, 2003.

On that day, US marines put a chain around the neck of a giant statue of Saddam in Baghdad's Firdoos Square, pulling it down in an action that has come to symbolise the dictator's overthrow.

A jubilant Iraqi crowd "insulted" the fallen statue by smacking its face with the soles of their shoes.

But five years on, the American military and Baghdad's new Shiite-led government are still battling to curb the bloodshed that has killed tens of thousands of people and displaced more than four million.

Ibrahim Khalil, one of the Iraqis who pulled down the statue in Firdoos Square, told AFP he regretted what he did that day.

"If history can take me back, I will kiss the statue of Saddam Hussein which I helped pull down," he said when he met an AFP reporter in the square.

"Now I realise that the day Baghdad fell was in fact a black day. Saddam's days were better ... Under Saddam's regime, we were safe. We got rid of one Saddam, but today we have 50 Saddams," he said.

Crowds of Sunni Arabs chanting "No! No! to occupation", held an anti-US protests in Baghdad's Adhamiyah district on Wednesday, although many Sunnis have now allied with the American military to fight Al-Qaeda in Iraq.

Fears of a resurgence in the violence are running deep after Sadr threatened on Tuesday to end the truce his feared Mahdi Army militia has been observing since August because of government attacks on his militiamen.

US commanders acknowledge that the ceasefire was one of the factors behind a sharp drop in violence across Iraq in the second half of last year.

On Wednesday, Iraqi President Jalal Talabani urged Sadr to disband the militia.

"I hope they respond to the demand of all political factions to disband the Jaish al-Mahdi (Mahdi Army). We will take all efforts to convince them and we have decided to hold a meeting with them to discuss the issue," Talabani said.

The US Iraq commander, General David Petraeus, urged in testimony to Congress on Tuesday that further troop withdrawals be put off for at least 45 days after the pullout of last year's troop reinforcements is completed in July.

Petraeus said the surge had helped make "significant but uneven" progress.

The White House said President George W. Bush was expected to implement the recommendations of Petraeus.

In view of "the president's practice of listening to his commanders on the ground, it would not be to type if he did not listen to them," White House spokeswoman Dana Perino said in Washington.

For Iraqis, the five years since the ouster of Saddam have been a period of turmoil and bloodletting.

"When I saw the American tanks roll into Baghdad, I was happy and full of dreams... dreams of a prosperous Iraq, a developed Iraq. But since then it has become a nightmare of suffering and destruction," said Sarah Yussef, 25.

According to World Health Organisation, between 104,000 and 223,000 people were killed from March 2003 to June 2006 alone.

Majeed Hameed, a gift-shop owner in Baghdad's northern Antar Square, said the American tanks on the streets of Baghdad are now seen as "enemy" forces.

"We can't describe how savage these barbarians are whose promises were false and full of lies. They came to occupy and cause destruction. We got nothing but disaster," said Hameed.