Washington, leading the calls for Syria to withdraw its forces from the country, said it welcomed promises by Damascus to do so but wanted to see deeds and not just words.

Many placards at Hizbollah's demonstration in the southern town of Nabatiyeh said "No to foreign intervention," but were aimed at the United States and Israel, not Syria.

"America out!" yelled supporters of the Syrian-backed Shi'ite Muslim group, mocking the chants of "Syria out" at opposition demonstrations in recent weeks.

It was the second time in a week the Hizbollah guerrilla group, Lebanon's most powerful political organization and the only one with weapons, had flexed its muscles.

Hundreds of thousands of people gathered in central Beirut on Tuesday to support Hizbollah's right to bear arms and to thank Syria for its role in Lebanon, where Damascus has kept troops since intervening in the country's civil war in 1976.

Waving Lebanese flags, the crowd chanted "Death to America, death to Israel" at the rally organized by Hizbollah and the smaller Shi'ite Amal party. A few burned U.S. and Israeli flags.

U.N. envoy Terje Roed-Larsen met Lebanese leaders and opposition figures on Sunday on United Nations resolution 1559, which calls for foreign forces to withdraw from Lebanon and the disarming of all militias there.

Roed-Larsen said he and President Emile Lahoud agreed at a "constructive" meeting that elections, expected in May, must go ahead on time. Political tensions had stirred talk of a delay.

Roed-Larsen last visited Lebanon days before the Feb. 14 killing of former Prime Minister Rafik al-Hariri, which sparked daily protests in Beirut against the Syrians many blamed.

Roed-Larsen said on Saturday Syrian President Bashar al-Assad had promised to withdraw all his troops and intelligence agents from Lebanon in line with the resolution.

He said he would present U.N. Secretary-General Kofi Annan next week with details on a timetable for a complete pullout.

Witnesses said personnel were packing up to leave at three main intelligence centers, taking down flags and huge pictures of Assad and his late father Hafez al-Assad.

Syrian troops left their posts in Mount Lebanon, northeast of Beirut. Some crossed the Syrian border, where several hundred Lebanese showered the departing soldiers with rice and flowers.

Washington cautiously welcomed Assad's promise to the U.N. envoy, having previously demanded Syria's immediate withdrawal.

"Initial reports are encouraging," White House national security adviser Stephen Hadley told U.S. Fox television on Sunday. "In the end of the day, it's going to be deeds, not words, that matter."

SUPPORT FOR HIZBOLLAH'S ARMS

Hizbollah, the main guerrilla group which fought Israeli occupation of Lebanon's south, was allowed to keep its arms after the civil war to fight Israeli forces occupying the south. It claimed credit for driving them out in 2000.

Foreign Minister Mahmoud Hammoud told reporters Lebanon's leaders had told Roed-Larsen they rejected the part of 1559 calling for militias in Lebanon to be disarmed.

"We said to him: We don't have any militias, we have a resistance that is supported by all the Lebanese people," he said.

Protesters, mostly Shi'ites but joined by Druze and others, came from across southern Lebanon to support Hizbollah's armed "Islamic resistance," witnesses said.

Some protesters held up Lebanese identity cards so that no one could say they had been bussed in from Syria, as some media reported happened at last week's Hizbollah rally in Beirut.

Lebanon's anti-Syrian opposition movement plans to hold a big demonstration in central Beirut on Monday, a month to the day since Hariri was killed. They have demanded an international investigation into his death.

A few thousand protesters held a candlelit vigil in Beirut's Martyrs Square on Sunday evening. Hundreds of flickering flames formed the word "Truth."