Beirut was transformed into a massive sea of red and white today as Lebanon marked the first anniversary of the assassination of the former prime minister, Rafik Hariri.

A demonstration in Beirut's Freedom Square, where Hariri is buried, drew hundreds of thousands of people into the city centre, where they observed a minute’s silence at 12:55 pm (1055 GMT).

The act of respect marked the exact time that a one-tonne truck bomb blast tore through the motorcade of the billionaire businessman and former Prime Minister, killing him and 20 other people, on Valentine’s Day last year.

"As Lebanese, rather than Christians and Muslims, let us cry ’Lebanon First’," said Hariri’s MP son Saad Hariri, addressing the massive crowd from behind a bullet-proof glass shield.

Nicholas Blanford, Beirut Correspondent of The Times, said that the demonstration matched in size some of the massive rallies seen after Hariri's murder, including one on March 14 last year, a month after the killing, that drew an estimated one million people - or one in four of the country's population - in a display of anger at Syrian domination.

Blanford said many speakers in today's demonstration focused their efforts on unseating Emile Lahoud, the Lebanese President whose term was controversially extended for three years under a Syrian-inspired amendment to the constitution in September 2004.

"Lahoud is the last pro-Syrian diehard and cuts a very lonely figure in his presidential palace overlooking Beirut," he said.

Syria, which pulled out its troops from Lebanon last April after a military presence spanning three decades, has been implicated in the Hariri murder by a UN commission of inquiry and several top officials have been interrogated.

Among those calling for Lahoud to stand down was Saad Hariri, who said that he remained the "symbol of (Syrian) domination". Walid Jumblatt, the veteran Druze leader, went a step further, branding Bashar al-Assad, the Syrian President, a "terrorist tyrant".

The city centre was closed to traffic amid a massive security deployment for the event. Pouring into the square by bus, car or on foot, demonstrators chanted "No, no to the mukhabarat" in reference to the once-feared Syrian secret police, as loudspeakers played patriotic songs and Koranic verses.

Apart from the red and white Lebanese flag, demonstrators also carried pictures of other politicians and journalists targeted in a wave of bombings against anti-Syrian figures over the past year.

"We are against terrorism, against confessionalism, for justice and the truth," the crowd chanted.

A rally last March 14, one month after the murder, drew a crowd of almost one million, one in four of Lebanon’s entire population. Hariri, now the head of the majority in parliament, has lived in France and Saudi Arabia in fear of his own life after a wave of attacks against prominent anti-Syrian politicians and journalists, some of them deadly, in the wake of his father’s slaying.

The United States, which has been leading the campaign against Syria, said yesterday that those responsible for the assassination would be brought to justice. "The international community will not rest until we get to the bottom of who is responsible and see that those responsible are held to account for what they have done," Sean McCormack, a State Department spokesman, told reporters.

Candlelit rallies and concerts as well as speeches are being held to remember Hariri. However, in a sign of continuing divisions, Hezbollah, the pro-Syrian Shia movement, and Michel Aoun, a key Christian leader, have refused to endorse the commemoration, claiming that it had been "politicised".

While Hezbollah opted not to call on its supporters to take part, another pro-Syrian Shia movement was holding its own commemoration in the southern port city of Tyre.

Hariri was buried in a mosque that he built on Martyrs’ Square, popularly renamed Freedom Square after his death. Beirut has been adorned with billboards in honor of Hariri, who played a major role in the reconstruction of the city after the 1975-1990 civil war. "We miss you," says one.

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