Hezbollah fighters seized control of rival pro-government strongholds in Beirut today as gunbattles rocked the Lebanese capital for a third day, edging the nation dangerously close to all-out civil war.

The Shia Muslim group, the most powerful armed movement in Lebanon, has also forced the shutdown of all media belonging to the family of Saad Hariri, the parliamentary majority leader, while a rocket hit the outer perimeter of his Beirut residence.

Gunfire and the thump of exploding rocket-propelled grenades echoed across west Beirut, where the fighting was concentrated between Sunni militants loyal to the Western-backed government and gunmen from the Shia opposition.

Red Cross officials said that at least 10 people were killed in the street battles that erupted yesterday after Hassan Nasrallah, the Hezbollah leader, called a government crackdown on his Iranian-backed Shia Muslim group a declaration of war.

“West Beirut plunges into urban warfare,” thundered the French-language daily L’Orient-Le Jour.

Witnesses said that several Sunni neighbourhoods in west Beirut considered bastions of Lebanon’s ruling bloc had been overrun by militants from Hezbollah and its ally Amal.

Fierce gunbattles also raged in the mixed Sunni-Shiite-Christian neighbourhood of Hamra where opposition militants also appeared to be gaining ground, AFP correspondents saw.

The latest unrest erupted on Wednesday during a general strike over price increases and wage demands which quickly degenerated into a confrontation between political rivals.

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 president since November, when the pro-Syrian Emile Lahoud stepped down.

The unrest has triggered urgent appeals for calm from the international community amid fears that a protracted political feud in multi-confessional Lebanon could descend into full-blown sectarian conflict.

Leaders of Lebanon’s ruling coalition have been called to an emergency meeting while Arab states are pushing for a special session of foreign ministers to tackle the crisis.

Lebanon’s already indebted economy could also be hard hit, with the forced shutdown of the country’s only international airport and the Beirut port and several major highways blocked by protesters.

“Everyone is running away,” said Imad, a 35-year-old businessman in a west Beirut neighbourhood as people rushed to stores that remained open to stock up, while others remained trapped in their homes by the fighting.

Armed militants were prowling about or hiding in buildings in the otherwise deserted streets of Beirut, in scenes reminiscent of the dark days of the 1975-1990 civil war.

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

Mr Hariri, whose father Rafiq Hariri was assassinated in 2005, had made a television appeal to try to calm the situation but this was rejected by Hezbollah.

“My appeal to you and to myself as well, the appeal of all Lebanon, is to stop the slide toward civil war, to stop the language of arms and lawlessness,” he said.

Gunmen firing rocket-propelled grenades surrounded the headquarters of Mr Hariri's Future Television and his movement’s Al-Mustaqbal newspaper early today. “All media channels have shut down and were placed under the control of the army after we received threats from armed elements of Hezbollah,” a company official said.

Air traffic was also paralysed for the third straight 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 is seen in the West as a terrorist outfit and 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,” Mr 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.

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