Hundreds of thousands of Lebanese marched through central Beirut today chanting "Syria Out" in the biggest protest yet against the influence of Damascus in Lebanon.

Crowds of men, women and children flooded Martyrs Square, spilling over into nearby streets, while more from across the country packed the roads into Beirut, responding to the opposition call to mark a month since the assassination of former Prime Minister Rafik Hariri.

The protest easily dwarfed the pro-Government rally of some 500,000, held last week by the Shia Muslim group Hezbollah. That show of strength forced the opposition to act to regain its momentum.

Syria's military withdrawal continued today, with about 50 intelligence agents closing two offices in northern Lebanon: in the town of Amyoun and in Deir Ammar on the coastal road linking the port city of Tripoli with the Syrian border, residents said.

Most intelligence offices, the widely resented arm through which Syria has controlled many aspects of Lebanese life, remained in northern and central Lebanon after Syrian troops moved east, closer to the Syrian border.

"We are coming to liberate our country. We are coming to demand the truth," said Fatma Trad, a veiled Sunni Muslim woman who travelled from the remote region of Dinniyeh in northern Lebanon to take part.

The opposition is demanding a full Syrian withdrawal, the resignations of Lebanese security chiefs and an international investigation into the February 14 assassination of Mr Hariri in a powerful bomb blast in Beirut.

Many were also particularly offended by pro-Syrian President Emile Lahoud's reinstatement last week of Prime Minister Omar Karami, who was forced to resign on February 28 by a giant opposition protest.

"They are challenging us, and we are here to show them that we will not accept," said Farid Samaha, a 32-year-old banker, as he joined the demonstration. "We are determined to liberate our country and we will not stop."

Last week, intelligence officers left two central towns, Aley and Bhamdoun, and headed to the Syrian-controlled areas of eastern Lebanon. The redeployment is the first stage of what Damascus says will be a full withdrawal, although it has not given a timetable.

A long line of people in Martyrs Square carried a 100-metre white-and-red Lebanese flag with the distinct green cedar tree in the middle, shaking it up and down and shouting, "Syria out."

Protesters sang the national anthem. Others chanted "Truth, Freedom, National Unity," or "We want only the Lebanese army in Lebanon."

There were no official estimates of the crowd size, but an Associated Press estimate put it at around 800,000 before the protest formally started, making it the biggest demonstration ever seen in this country of 3.5 million.

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