Hundreds of soldiers and police blocked off Beirut's central Martyrs' Square, but there was no violence, even as more and 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.

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 former Prime Minister Rafik 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 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 a light rain, waving the national flag and chanting, "We want no other army in Lebanon except the Lebanese army!" About 3,000 had spent the night in the square to beat the ban on demonstrations, which took effect at daybreak Monday.

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