NAJAF, Iraq – Iraq’s top Shiite cleric, Grand Ayatollah Ali al-Sistani, made a dramatic return to Najaf yesterday and swiftly won agreement from a rebel cleric and the government to end three weeks of fighting between his rebel fighters and American-Iraqi forces.

The renegade Muqtada al-Sadr accepted the proposal in a face-to-face meeting last night with the 75-year-old Ayatollah al-Sistani. Hours afterward, Iraq’s interim government also agreed to the deal.

Ayatollah al-Sistani’s highly publicized, 11th-hour peace mission would almost certainly boost his already high prestige in Iraq and cloak him in a statesman’s mantle, showing that only he had the ability to force an accord between two sides that loathe each other.

The influential cleric returned to Iraq after heart treatment in London to intervene for the first time in the bloody conflict, drawing thousands of followers who marched on Najaf and massed on its outskirts.

In the 24 hours before Ayatollah al-Sistani entered the holy city, more than 90 Iraqis were killed in fighting – including 27 killed when mortars barraged a mosque in neighboring Kufa, where thousands had gathered to march into Najaf in support of Ayatollah al-Sistani’s mission.

Meanwhile, an Arab television station said Friday that it received a video showing the killing of kidnapped Italian journalist Enzo Baldoni, whom insurgents had threatened to execute if Italy did not withdraw troops from Iraq. Al Jazeera said the video was too graphic to broadcast but appeared to show Baldoni being slain.

Prime Minister Berlusconi, a staunch supporter of the American-led war to topple Saddam Hussein’s regime, condemned the reported slaying and repeated his statement of Tuesday that Italy’s 3,000 soldiers would not abandon the American-led coalition and Iraq’s government.

Fighting eased in Najaf after Ayatollah al-Sistani arrived, and the American military and the Iraqi government called a 24-hour ceasefire.

The acceptance by the young firebrand preacher Mr. al-Sadr – whose rebel fighters have been battling American and Iraqi forces since August 5 – didn’t necessarily mean an end to the crisis. He has agreed to peace proposals before, and they have quickly fallen apart.

But the state minister, Qassim Dawoud, announcing the administration’s acceptance, was optimistic. “Brothers, we have entered the door to peace,” he said. He added that the government would not try to arrest Mr. al-Sadr, who is sought in the slaying of a rival cleric last year.

The five-point plan calls for Najaf and Kufa to be declared weapons-free cities, for all foreign forces to withdraw from Najaf, for police to be in charge of security, for the government to compensate those harmed by the fighting, and for a census to be taken to prepare for elections expected in the country by January.

There was no immediate word if the American military would accept the provisions on the agreement calling on its forces to leave Najaf. In Washington, a senior Bush administration offi cial, speaking on condition of anonymity, said only: “We’ve seen the developments. We’re watching them very closely.”

Mr. Dawoud said American and coalition forces would pull out of Najaf as soon as interim Prime Minister Allawi ordered them to.

Ayatollah al-Sistani’s aide, Hamed al-Khafaf, announced Mr. al-Sadr’s acceptance and suggested fighters from his Mahdi Army would leave the Imam Ali Shrine, the holy site they have used as a stronghold and refuge throughout the fighting.

“There will be a mechanism that will preserve the dignity of everyone in getting out of the holy shrine, and you’ll see this in the coming hours,” Mr. al-Khafaf told Al Jazeera television.

The shrine, in Najaf’s Old City, has been the center of fighting, but American troops have tried to avoid damaging it, fearing it would anger Shiites.

After the cease-fire was called, one platoon of American soldiers was holed up in a multistoried office building, poking weapons out of broken windows and scanning devastated streets for any signs of insurgents. A handful took advantage of the quiet to sleep – a relative luxury after days of fierce clashes, according to Associated Press photographer Jim MacMillan, who is embedded with the soldiers.

Ayatollah al-Sistani’s immense moral authority brings more hope for the new peace plan than previous ones.

As the most senior of four clerics in Iraq holding the rank of grand ayatollah, Ayatollah al-Sistani is one of the most respected men in the country, esteemed by Iraqis of all religious factions. He is more popular among Iraqi Shiites than Mr. al-Sadr, who is in his early 30s and of a far lower clerical rank.

Mr. al-Sadr’s fiery anti-American message has drawn many poorer, disillusioned Shiites but he is seen by the Shiite mainstream as impulsive and too radical.