The sectarian fighting had eased by early afternoon as the army and police moved across areas now in the hands of Shiite opposition forces who fired celebratory gunshots wildly into the air after routing Sunni militants loyal to the Western-backed government.

"There are no clashes anymore because no one is standing in the way of the opposition forces," a security official said on condition of anonymity.

But as the guns fell largely silent, it was unclear what the immediate future would hold for Lebanon, amid fears the protracted political feud could plunge the nation back to the dark days of the 1975-1990 civil war.

Earlier Friday, terrified residents cowered inside as the rattle of gunfire and the thump of exploding rocket-propelled grenades rung out across mainly Muslim west Beirut as Sunni government loyalists fought Shiite gunmen.

At least 11 people have been killed and dozens wounded in fighting that erupted on Thursday after Hezbollah chief Hassan Nasrallah said a government crackdown on his powerful militant group was a declaration of war.

The unrest triggered urgent international appeals for calm, while Arab nations led by regional powerhouse Saudi Arabia are pushing for a special session of foreign ministers to tackle the crisis.

Lebanon's feud is is widely seen as an extension of the confrontation pitting the United States and its Arab allies and Israel against Syria and Iran, which back Hezbollah -- regarded as a terrorist group by the West.

Several states have begun pulling out their nationals from Lebanon, which less than two years ago was devastated by a war between Hezbollah and Israel that left more than 1,200 people dead.

Beirut residents were fleeing for shelter elsewhere as tanks rolled through the streets and hundreds of riot police and troops patrolled the city, but they have been ordered not to intervene.

Lebanon was largely cut off from the outside world, with the international airport and Beirut port shut and some roads to neighbouring Syria blockaded by burning tyres.

Christian leader Michel Aoun, who is allied with Hezbollah, welcomed the opposition triumph, saying: "What happened today is a victory for Lebanon."

An official with the ruling majority said the Future Movement of Sunni political leader Saad Hariri had handed over control of its institutions, including media outlets and social services offices, to the army to avoid a further escalation.

"There are no clashes taking place anywhere, there are just people shooting in the air," he said, stressing that the ruling bloc had instructed its militants not to engage in fighting with the opposition.

Witnesses recounted the chaos and fear that reigned in Beirut overnight as people rushed to stores that remained open to stock up, while others were trapped in their homes.

"It was a hellish night. The armed militants were everywhere shooting all over the place," said west Beirut resident Rima.

Although west Beirut was virtually under siege, in the predominantly Christian eastern sector of the city, life was going on as usual, with shops and other businesses open.

Israeli President Shimon Peres claimed the violence was fomented by archfoe Iran to further what he said was Tehran's goal to control all of the Middle East.

Syrian President Bashar al-Assad -- whose country is Iran's closest regional ally -- said the unrest was a purely "internal affair" but called for dialogue.

Air traffic was paralysed for a third day with no flights scheduled to land or take off from Beirut international airport, an airport official said, after Hezbollah supporters blocked access with mounds of earth and burning tyres.

Nasrallah delivered his defiant speech on Thursday after the government launched a probe into a private communications network run by Hezbollah, which critics say has become a "state within a state."

"The decisions are tantamount to a declaration of war and the start of a war... on behalf of the United States and Israel," Nasrallah charged. "The hand that touches the weapons of the resistance will be cut off."

The United States delivered a blunt warning to Hezbollah to stop its "disruptive activities" while UN Security Council members said they were "deeply concerned" over the crisis, a view reflected by other Arab and European leaders.

The crisis will be the focus of talks between President George W. Bush and Lebanese Prime Minister Fuad Siniora in Egypt next week during the US leader's tour of the Middle East.

Regional powerhouse Saudi Arabia, which backs the Siniora government, called for an urgent meeting of Arab foreign ministers, which an Egyptian official said could be held in two days.

Yemen suggested army chief Michel Sleiman, the consensus candidate in efforts to fill a presidential vacuum in Lebanon, be mandated to chair a dialogue to resolve the crisis.

The long-running political standoff, which first erupted in November 2006 when six pro-Syrian ministers quit the cabinet, has left the country without a head of state since November, when pro-Syrian Emile Lahoud stepped down.

While the rival factions have agreed on Sleiman, they disagree on the make-up of the new cabinet and so far 18 sessions of parliament to choose a president have been cancelled.

© 2008 Agence France-Presse