Defying a ban on protests, about 10,000 people demonstrated against Syrian interference in Lebanon on Monday, as opposition lawmakers sought to bring down the pro-Damascus government two weeks after the assassination of former Prime Minister Rafik Hariri (search).

Hundreds of soldiers and police blocked off Beirut's central Martyrs' Square (search), but there was no violence, even as more protesters managed to evade the cordon and join the demonstration.

Protest leaders urged their followers not to provoke the security forces, who refrained from trying to disperse the crowd.

Also, Syrian President Bashar Assad (search) denied involvement in Hariri's killing, telling an Italian newspaper that would have been an act of "political suicide" for Damascus. Assad also said he was convinced the United States will realize that his country is essential to peace efforts in the Middle East and in Iraq.

Opposition legislators sought to bring down the pro-Syrian government of Prime Minister Omar Karami in Monday's confidence debate. It was the first time the legislature discussed the Feb. 14 assassination of Hariri, who was killed with 16 other people in a massive bomb blast.

"The assembly seeks answers to one question: 'Who killed Rafik Hariri?"' parliamentary speaker Nabih Berri said as he opened the debate, calling on the government to expedite its investigation.

Many Lebanese say Karami's administration and Syria were behind the attack — a charge both governments deny.

The session began with a moment of silence for the slain legislator.

Then Hariri's sister, legislator Bahiya Hariri, addressed the parliament and called on the government to resign.

"All the Lebanese want to know their enemy, the enemy of Lebanon who killed the martyr Rafik Hariri, those who took the decision, planned and executed it, those who ignored and prevented the truth from coming out," Bahiya Hariri said, struggling to hold back tears.

Karami asked parliament for a vote of support, outlining his government's accomplishments and promising to hold elections as scheduled in April and May.

About 200 yards away, the demonstrators stood in a light rain, waving the national flag and chanting, "We want no other army in Lebanon except the Lebanese army!" About 3,000 spent the night in the square to beat the ban on demonstrations, which took effect at daybreak Monday.

The assassination of Rafik Hariri has intensified world and Lebanese opposition pressure for Syria to withdraw its 15,000 troops from Lebanon.

U.S. Deputy Assistant Secretary of State David Satterfield is scheduled to meet Lebanon's foreign minister Monday to press the message.

Shortly before Satterfield met with a Sunni Muslim spiritual leader Monday, about a dozen plainclothes gunmen carrying assault rifles appeared on a Beirut street, Lebanese security officials and witnesses said.

An advance team of U.S. security guards detected the gunmen and alerted the Lebanese military, the officials said. Lebanese troops went quickly to the Aisha Bakkar neighborhood where the country's Sunni Muslim grand mufti, Sheik Mohammed Rashid Kabbani, has his offices.

By the time soldiers arrived, the gunmen had left, Lebanese security officials said on condition of anonymity.

On Sunday, Satterfield reiterated Washington's demand that Syria withdraw its troops from Lebanon "as soon as possible."

Syria said Thursday it would move its troops eastward toward its border, but they would not leave Lebanon. By Monday, there was no sign the redeployment had begun.

In an interview published Monday in the Italian newspaper La Repubblica, Assad denied involvement in Hariri's killing, and he also reiterated that Syrian troops would remain on Lebanese territory.

"Under a technical point of view, the withdrawal can happen by the end of the year," he said. "But under a strategic point of view, it will only happen if we obtain serious guarantees. In one word: peace."

Hariri was seen as quietly opposing Syria's control over Lebanon and had been expected to oppose Karami in the elections.

Opposition leader Walid Jumblatt urged legislators to vote against the government Monday, saying a vote of confidence in the government would be "another assassination of Hariri."

Speaking on local TV, Jumblatt said Lebanese were not hostile to Syrians, "but we tell them: 'Leave us. Leave us. Leave us."'

"We don't want Lebanese and Syrian intelligence controlling Lebanon. We want to know who killed Rafik Hariri," said the leader of Lebanon's Druse.

He spoke from his ancestral mountain palace in Mukhtara, 19 miles southeast of Beirut, where he has been holed up for days for fear of assassination.

Interior Minister Suleiman Franjieh banned protests on grounds of "supreme national interests and maintaining national peace." He ordered all security forces to take "all measures necessary to maintain security and order and prevent demonstrations and gatherings."

Security forces did manage Monday to stop protesters from reaching the prime minister's office, which was cordoned off by soldiers, anti-tank obstacles and barbed wire.

Hundreds of troops, many in armored personnel carriers, set up roadblocks at entrances to central Beirut, turning back flag-waving teenagers, reducing traffic to a trickle and making the city appear as if it were under siege.

The debate in parliament began late as many legislators were delayed by the traffic jams. Many commuters abandoned their cars on the side of the road and walked through the roadblocks to the city center.