Thousands of protesters kept up their efforts to bring down Lebanon's U.S. backed government on Saturday, camping out in the capital and disrupting life in the city's commercial district.

Hezbollah officials said their attempts were designed to bring down Prime Minister Fouad Saniora's government, and pledged they would not back down until a national unity government has been established.

However, Saniora showed no sign of wavering in the face of the protests.

The demonstrations have been largely peaceful so far, however there is potential for violence as large groups of protesters come into close range with heavily-armed police and members of the military.

Barbed wire and armoured military vehicles have so far kept the protestors out of government headquarters where Saniora and some of his ministers are waiting out the storm.

Some newspapers called the standoff the "great showdown."

Initially, hundreds of thousands of Lebanese protesters began pouring into central Beirut on Friday.

Police estimated the group was 800,000-strong but Hezbollah officials said there were at least one million protesters -- which would be one-fourth of Lebanon's population.

Even roads leading to the prime minister's headquarters were closed off.

Shiite Muslim Hezbollah groups were bused in from all over Lebanon to downtown Beirut for the rally that was intended to be followed by an indefinite sit-in near the government offices.

After the rally, participants set up hundreds of white tents across the city centre -- with a cluster of about 12 located just metres from Saniora's offices.

Some media outlets estimated 500 tents were set up.

On Saturday, the demonstrators kept up the noisy, carnival-like protests with occasional shouts of "Saniora out!"

Hezbollah supporters also set up water tanks and portable latrines and distributed sandwiches, tea and coffee to those who were camping out.

"Yesterday's demonstration was just the beginning. There are a lot of other surprises on the way," Ali Ammar, an 18-year-old student who had just woken up, told The Associated Press. "This government lost the trust of the people a long time ago, and we will not stop until it goes."

Hezbollah, supported by Syria and Iran, is staging the protest against a government they've deemed a puppet of the United States.

The tight security, which included 16 armoured personnel carriers, came amid fears of street clashes and violence between pro- and anti-Syrian factions within Lebanon.

Some area schools were closed Friday and businesses near the gathering place of the protesters shut down.

A defiant Saniora said Thursday that his government would not be overthrown.

"Lebanon's independence is threatened and its democratic system is in danger," said Saniora.

Government supporters say the rally is an attempt by Syria to regain control within the country after they were pushed out in April 2005. Hezbollah supporters say they need to regain their rightful portion of power to combat U.S.-influences in the country.

"People have a right to express their political opinions, but in terms of this being part of the Iran-Syria inspired coup d'etat against the government of Lebanon, we're obviously quite concerned about it," U.S. Ambassador to the United Nations John Bolton told The Associated Press.

Hezbollah has threatened the protests in the past unless the group and its allies were given a veto-wielding share of the cabinet. Those demands have been rejected by Saniora and the anti-Syrian parties.

Hezbollah's deputy leader Sheik Naim Kassim said the fight against "American tutelage" will continue until the government falls.

Critics of the government also say it did not do enough to back Hezbollah during the July-August war with Israel. Meanwhile, pro-government groups blame Hezbollah for sparking the war, by taking two Israeli soldiers hostage, and dragging Lebanon into the conflict.

Saniora's government

The government is already in a weakened state with the resignation of six opposition ministers and the Nov. 21 assassination of anti-Syrian Christian cabinet minister Pierre Gemayel.

Gemayel's death drew hundreds of thousands of anti-Syrian protesters to Beirut.

Many within the anti-Syrian camp accuse the opposition of trying to derail an international tribunal into the death of assassinated former Prime Minister Rafik al-Hariri.

Just last Saturday, Saniora's government approved the tribunal to try suspects believed to be involved in the murder.