Hundreds of thousands of supporters of the radical Shia cleric Moqtada al-Sadr took to the streets of two Shia holy cities in Iraq today and protested against "US occupiers".
The rally was called by Mr Sadr, who said in a statement yesterday that his militia followers should redouble efforts to drive US forces out of Iraq, describing them as "your arch-enemy".
Today, clad in Iraqi flags, demonstrators marched from the city of Kufa to neighbouring Najaf, which is 100 miles south of Baghdad, shouting "we obey your call" and other slogans against the US "occupiers".
BBC News reported that up to 1 million Shias were expected to take to the streets in Najaf.
Yesterday thousands of residents in Baghdad's largest Shia slum, Sadr City, boarded buses and minivans bound for Najaf for today's rally, which was choreographed to mark the fourth anniversary of Baghdad's fall.
At today's demonstration, leaflets fluttered through the breeze reading: "Yes, Yes to Iraq" and "Yes, Yes to Moqtada. Occupiers should leave Iraq."
The US military spokesman, Rear Admiral Mark Fox, said that four years ago US-led forces had "liberated Iraq from Saddam's republic of fear". That had allowed Iraqis to exercise their democratic rights and stage protests such as today's, he said.
He acknowledged, however, that despite there being "substantial accomplishments, the first four years have also been disappointing, frustrating and increasingly dangerous in many parts of Iraq".
The demonstration was peaceful, with two cordons of Iraqi police lining the route. Two ambulances could be seen moving slowly with the marching crowd, poised to help if violence or stampedes broke out.
Mr Sadr commands an enormous following among Iraq's majority Shia population and has close allies in the Shia-dominated government.
As he marched, politician Nassar al-Rubaie, head of Mr Sadr's bloc in parliament, said: "The enemy that is occupying our country is now targeting the dignity of the Iraqi people ... After four years of occupation, we have hundreds of thousands of people dead and wounded."
Mr Sadr's statement yesterday called for Iraq's army and police to join him in defeating the US.
Today some Iraqi soldiers in uniform joined the crowd, which was led by at least a dozen turbaned clerics - including one Sunni.
Many marchers danced as they moved through the streets.
Security was tight across Iraq, with vehicles banned from the streets in areas affected by the protest march and in Baghdad.
Reacting to the plans for the rally, the government had quickly reinstated today as a holiday, just a day after it had decreed that April 9 no longer would be a day off.
Mr Sadr had reportedly ordered his militia to disarm and stay off the streets during a Baghdad security crackdown by the US and Iraqi forces that began February 14.
However, the cleric has nevertheless recently issued a series of sharp anti-American statements, demanding the immediate withdrawal of US troops.
US officials have said Mr Sadr left Iraq for neighbouring Iran after the start of the Bush administration's "surge" of almost 20,000 new troops in the capital, but his followers say he is in Iraq.
Yesterday's statement from the cleric was apparently issued in response to three days of clashes between his Mahdi army militiamen and US-backed Iraqi troops in Diwaniya, which is 80 miles south of Baghdad.
American troops continued operations in Diwaniya today, detaining four guards at a the office of a Shia political party and scouring two neighbourhoods in the city's northern and eastern sections, Iraqi police said. At least 24 suspects were detained, police said.
Also yesterday, Iraq's foreign minister, Hoshyar Zebari, warned that Iraq should not become a crucible for the US and its regional foes Iran and Syria. He said Iraq's security should be the "only issue on the agenda" of a major international conference aimed at finding ways to stabilise the strife-torn country.
On the fourth anniversary of Baghdad's fall to United States forces, tens if not hundreds of thousands of Iraqis marched peacefully in protest of the continued occupation. Wearing Iraqi flags, demonstrators marched from Kufa to Najaf chanting "Get out, get out occupier!" Many were dancing through the streets as police kept an eye on the proceedings and lined the route.

The rally was largely Shi'ite, as it had been ordered by controversial cleric Muqtada al-Sadr. Leaflets were scattered about, reading "Yes, Yes to Muqtada!" and "Yes, Yes to Iraq!" Some demonstrators shouted "we obey your call," seemingingly in response to al-Sadr's statements on Sunday.



Al-Sadr called the demonstration in a statement that was distributed in Najaf yesterday. In the statement he ordered for his supporters to stop attacking their fellow Iraqis and instead work to fight the American occupiers. He also encouraged the Iraqi army and police to stop cooperating with America. "You, the Iraqi army and police forces, don't walk alongside the occupiers, because they are your archenemy," the statement said. "God has ordered you to be patient in front of your enemy, and unify your efforts against them - not against the sons of Iraq."