By Nadim Ladki , BEIRUT (Reuters) – A crowd of 500,000 flag-waving Lebanese packed a square in central Beirut on Tuesday to mark the first anniversary of the assassination of former Prime Minister Rafik al-Hariri. The turnout, reminiscent of huge protests after the February 14 2005 murder that forced Syria to bow to international pressure and leave Lebanon, looked set to give fresh impetus to the country’s anti-Syrian coalition that dominates the government after winning a general election in May and June.

The coalition of Sunni Muslim, Christian and Druze political forces, which called the rally, is demanding to know the truth about Hariri’s assassination, which it blames on Damascus, and the resignation of President Emile Lahoud."We miss you," read large posters of Hariri. "They feared you, so they killed you," others said. "He lived Lebanon and died for its sake," a black banner read.

Security officials estimated the crowd at 500,000. The rally’s organizers and allied acting interior minister put the number at over 1 million, more than a quarter of Lebanon’s 4 million people. All schools, shops, banks and businesses in the country were shut for the occasion.

"I came here to say that the terrorist Syrian regime that kills will never escape punishment," Amal Yassin, a mother of three, told Reuters as she waved a red-and-white Lebanese flag.

Leaders of the coalition, including Hariri’s son Saad al-Hariri, were expected to address the crowd, estimated by security sources at half-a-million of Lebanon’s 4 million population.

Shi’ite Muslims, led by Syrian and Iranian ally Hizbollah, largely stayed away from the rally.

Thousands of Lebanese soldiers and police were deployed in Beirut and its suburbs as people converged from across Lebanon on Martyrs’ Square in downtown Beirut, where Hariri is buried.

Security measures were tightened after a demonstration against cartoons depicting Prophet Mohammad turned into a riot in which the Danish mission was torched and a church vandalised earlier this month.

U.N. INQUIRY

"We salute the Lebanese for coming together around a just cause … and displaying their unity," Cardinal Nasrallah Sfeir, the Maronite patriarch, told LBC television.

Many in Lebanon say Syria was behind the killing of Hariri. A United Nations inquiry has implicated senior Syrian security officials and their Lebanese allies. Damascus denies any role.

Four pro-Syrian generals have been detained and charged with roles in the murder, but no indictments have yet been issued.

A poster carried the pictures of the four and that of Lahoud above a sentence reading: "Four down, one to go".

The killing of Hariri, a billionaire construction tycoon and prime minister for 10 years between 1992 and 2004, galvanised international sympathy and support for Lebanon and piled pressure on Syria.

One of Hariri’s personal friends was French President Jacques Chirac, the driving force behind several U.N. Security Council resolutions on Lebanon and the Hariri investigation.

"I can tell you that the international community’s determination to find and punish the guilty, on the one hand, and to give Lebanon all the means for independence, security, democracy and freedom, on the other hand, has not moved at all," Chirac told Future Television on the eve of the anniversary.

But despite the Syrian pullout in April, a string of bombings and the assassination of three anti-Syrian figures as well as a series of political crises and the resurfacing of sectarian tensions have raised fears Lebanon could slide into instability.

(Additional reporting by Leila Bassam and Alaa Shahine)