Iraq's Shiite spiritual leader Grand Ayatollah Ali al-Sistani arrived in Najaf on Thursday as a huge crowd of people forced their way into the city's holy shrine calling for peace in the city.
A 24-hour ceasefire began immediately upon his arrival on the order of Prime Minister Iyad Allawi - although the local governor said hostilities would resume if a solution to the standoff against Shiite militia was not found by then.
The US Army confirmed a military offensive against Sadr's militiamen in Najaf has been temporarily suspended to allow for peace talks.
The assault had been "temporarily suspended" to facilitate the return of Iraq's top Shiite cleric Grand Ayatollah Ali al-Sistani and allow for talks between his representatives and those of rebel cleric Moqtada Sadr, it said.
But Sistani's arrival was marked by a deadly day in Najaf's twin city of Kufa, where 74 people were killed and 376 wounded in a mortar attack on the main mosque and shooting at a march which was blamed on Iraq's national guard, the health ministry said.
After a seven-hour journey, Sistani's motorcade stopped in Al-Saad one of the few relatively smart districts of Najaf, where the elderly Iranian-born cleric went to rest in a house.
Iraqi police and national guardsmen swarmed outside and blocked off the street as a stream of visitors flocked to the area.
"He's in good health, but he's tired from the trip and he cannot talk to anyone right now," said Najaf police chief Ghaleb al-Jazairi.
With military operations called off, an enormous crowd forced its way into Najaf's revered Imam Ali mausoleum, which has been trapped off from the outside world by heavy US bombardment and tank fire since Wednesday.
Rebel cleric Moqtada Sadr has used the shrine as the headquarters of his Mehdi Army since his spring uprising against foreign troops.
"We answered the call of Sistani who ordered us to follow to Najaf to break the siege. Police sort of tried to arrest us, but there was nothing they could do. It's the end of the siege," said one demonstrator Kazem Hamid.
"We have started contacts with Moqtada Sadr and in the coming hours we are waiting, hoping that we will succeed in saving the city from destruction," said Sistani spokesman Ahmed al-Khaffaf, calling on people not to enter Najaf.
"Demonstrators outside Najaf will only be admitted to the city after they have been searched," he said.
Inside the shrine, Medhi Kadhem Ali, commander of the militia's mortar division confirmed that US troops were still heavily deployed.
"There is a truce, but the Americans have only withdrawn from the market in the Old City. They are still deployed along the edge of the cemetery and in the sea of Najaf," he said.
He said US troops opened fire on fighters who had tried to retrieve dead and wounded stranded for days.
"I hope that this is the end of the battle, but we have to wait for the result of the talks," he said.
Sistani's giant, ragged convoy, greeted by thousands and escorted by police and national guard patrol vehicles, crawled along at 20 kilometres (12 miles) an hour on the long 400-kilometre (250-mile) journey north from Basra.
At towns along the way, men, women, children and the elderly, lined the streets to greet Sistani, regarded as moderating influence in Shiite Islam.
Behind the vehicles containing the ayatollah and his aides, more than 1,000 cars, pick-up trucks, taxis and buses were packed with Shiite faithful of all ages, waving banners and pictures of Sistani.
Many were supporters of Sadr during his three-week battle against US and Iraqi government forces has endangered the Imam Ali mausoleum in Najaf, one of the most sacred sites in Shiite Islam.
"We are here for the peace rally to stop the bloodshed in Najaf. It is the city of peace and we're answering Sistani's call," said Jaffar Salih, 38, hanging out of a taxi.
Sistani returned to Iraq on Wednesday via Kuwait from London, where he had gone three weeks before for treatment for a heart problem just as the Najaf fighting erupted.
His hurried return came after US forces smashed militia defences to trap hundreds of Sadr's supporters in the Imam Ali shrine.
Under US airstrikes, tanks rolled up to within 20 metres (yards) of the mosque and at dawn Thursday four bullet holes were visible in the golden dome.