BEIRUT (AFP) - - The Lebanese capital braced for more sectarian violence Friday after fierce gunbattles in Beirut left at least seven people dead and the opposition Hezbollah chief charged that a government crackdown on his group was tantamount to a "declaration of war".

The international community launched urgent appeals for calm in the deeply divided country after two days of clashes between rival political factions that signalled a major escalation in a bitter 18-month power struggle.

Thursday's shootouts between supporters of the Western-backed government and the Hezbollah-led opposition in mixed Sunni and Shiite Muslim districts of the capital also left dozens wounded, hospital and security officials said.

In scenes ominously reminiscent of the 1975-1990 civil war, Beirut's streets were virtually deserted during the day as loud explosions and gunfire rang out, while gunmen, some hooded, fired rocket-propelled grenades and machine guns.

The United States delivered a blunt warning to the Iranian- and Syrian-backed Hezbollah to stop its "disruptive activities" while UN Security Council members said they were "deeply concerned" over the crisis.

Hezbollah chief Hassan Nasrallah delivered his fiery speech on the second day of anti-government protests which saw supporters of the feuding factions block roads with blazing tyres and force the closure of Lebanon's international airport.

"The (government) decisions are tantamount to a declaration of war and the start of a war... on behalf of the United States and Israel," Nasrallah charged during a rare press conference.

The government on Tuesday launched a probe into a private communications network run by the powerful Shiite movement, which is seen in the West as a terrorist outfit and which critics say has become a "state within a state."

"The hand that touches the weapons of the resistance will be cut off," Nasrallah warned. "We have the right to confront he who starts a war with us by defending our rights and our weapons."

Nasrallah said Hezbollah was ready for dialogue but demanded the government rescind its measures against his movement.

Hezbollah flatly rejected proposals by the government bloc to end the clashes, the group's Al-Manar television reported after parliamentary majority leader Saad Hariri demanded an end to the "siege" of Beirut.

And an official with the ruling coalition said armed Hezbollah militants had broken into offices of Hariri's Future Movement.

"We have given instructions to our supporters not to engage in a civil war but we have also told them to defend themselves if attacked in their homes."

Underscoring fears of continued instability, people rushed to stores to stockpile food and bread, while the United Arab Emirates began evacuating its nationals from Beirut.

"Hezbollah needs to make a choice: Be a terrorist organisation or be a political party, but quit trying to be both," said US national security council spokesman Gordon Johndroe. "They need to stop their disruptive activities now."

He said US President George W. Bush would discuss the turmoil when he meets Lebanese Prime Minister Fuad Siniora in Egypt next week during a Middle East tour.

Regional powers Egypt and Saudi Arabia voiced support for the Siniora government, and Arab League chief Amr Mussa, who has embarked on several missions to try to resolve the crisis, urged Lebanon's leaders to avoid any further escalation.

Former colonial power France described the renewed fighting as "worrying" and called for restraint, while the EU also told Hezbollah to start playing a "constructive role."

UN Middle East envoy Terje Roed Larsen told the Security Council that Hezbollah's separate paramilitary infrastructure "constitutes a threat to regional peace and security."

Israel, which fought a devastating war with Hezbollah in 2006, said it had no comment on the events in its northern neighbour, with foreign affairs spokesman Arye Mekel bluntly stating: "It's none of our business."

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 crisis has left the country without a president since November, when pro-Syrian Emile Lahoud stepped down.

While the rival factions have agreed to the election of army chief Michel 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.