BEIRUT (AFP) - - Fierce fighting erupted in northern Lebanon on Monday, further exacerbating tensions after days of deadly sectarian battles that have driven the nation to the brink of full-blown civil war.

At least one man was killed in clashes between supporters of the Western-backed government and militants loyal to the Shiite Hezbollah-led opposition in the port city of Tripoli, a security official said.

By late afternoon the fighting had died down as the army moved in, appealing to militants to get off the streets.

The army said it will use force if necessary from Tuesday to disarm gunmen and restore law and order after six days of fighting left at least 61 people dead and nearly 200 wounded.

It was the worst internal unrest since the 1975-1990 civil war and dramatically raised the stakes in a protracted political crisis.

After foreign ministers held weekend crisis talks in Cairo, an Arab League delegation prepared to visit Beirut on Wednesday in a bid to end the fighting which some fear could engulf other parts of the volatile region.

Hezbollah welcomed the Arab League decision but insisted that the delegation must be neutral: "We ask the Arabs not to favour one party over another," Hezbollah deputy chief Hussein Khalil told a news conference.

The showdown saw Hezbollah gunmen seize large swathes of Muslim west Beirut last week, plunging an already fragile nation into fear and uncertainty.

The international community reacted with alarm to the fighting, which the United States blames on the powerful Hezbollah and its Syrian and Iranian patrons.

On Monday, Lebanese troops moved into the Druze mountains southeast of the capital after weekend firefights between rival factions killed at least 16 people.

"Following the events of recent days, namely in Beirut and in the mountains, army units have bolstered their deployment in zones of tension and are working to ensure security, re-establish order and ban all armed presence," an army statement said.

"Army units will ban collective or individual irregularities in line with legal procedures, even if this means using force," it said. "This decision will be effective starting at 0600 (0300 GMT) on May 13."

Uneasy calm gripped Beirut where the road to Beirut international airport was shut for the sixth straight day and a border crossing into Syria was also blocked.

The Saudi ambassador to Lebanon and his family were among 200 people who managed to reach the nearby island of Cyprus by boat, officials there said.

Clashes turned deadly on Thursday after Hezbollah leader Hassan Nasrallah accused the government of declaring war against his party.

The violence erupted after the government said it would investigate a Hezbollah telephone network and reassign the airport security chief over his alleged links to the militant group.

But opposition fighters withdrew from Beirut's streets on Saturday after the army acted to overturn the decisions.

Sunni Muslim Prime Minister Fuad Siniora has accused the opposition of staging a coup in the multi-confessional nation, which has been without a president since November amid a political standoff.

The violence and Sunni-Shiite rivalries raised fears that the situation could further escalate.

The crisis is widely seen as an extension of the regional confrontation pitting the United States and its Arab allies against Syria and Iran.

Ahead of a visit on Wednesday to Israel, US President George W. Bush on Monday called Iran "the single biggest threat" to Middle East peace and accused Tehran of "funding Hezbollah".

"Their funding of Hezbollah -- look what's happening in Lebanon now, a young democracy trying to survive," Bush told Israel's Channel 10 television.

His secretary of state Condoleezza Rice described the situation in Lebanon as "very fragile" before taking part in a conference call on the crisis with officials from Arab and European countries and the United Nations.

"There is no solution to the present crisis other than dialogue," the European Commission's external relations commissioner Benita Ferrero-Waldner said in a statement issued in Brussels after she spoke to Siniora by telephone.

UN chief Ban Ki-moon also urged a return to dialogue and said he "strongly condemns those responsible for the violence," a statement said.

Saudi Arabia warned that the fighting served only "foreign extremists who have undermined every sincere and honourable effort aimed at ending Lebanon's political crisis," the official SPA news agency reported.

In Beirut parliament speaker and opposition stalwart Nabih Berri postponed a 19th attempt to elect a president, scheduled for Tuesday, until June 10, the private LBC television channel reported.

The political standoff, which erupted in November 2006 when six pro-Syrian ministers quit, has left Lebanon without a president since November when Damascus protege Emile Lahoud's term ended.