Thousands of flag-waving Lebanese gathered in Beirut on Wednesday to lay to rest anti-Syrian newspaper publisher and legislator Gebran Tueni, whose assassination has been blamed on Damascus.

Tueni was killed on Monday by a car bomb in a Christian suburb of Beirut in the third political murder since former Prime Minister Rafik al-Hariri was assassinated in February.

"All of Lebanon bids goodbye today to the martyr of free speech Gebran Tueni," said the frontpage headline of al-Mustaqbal newspaper, owned by the late Hariri.

Anti-Syrian politicians have called for a large turnout to Tueni's funeral procession, due to wind through the streets of Beirut from a Greek Orthodox church in the heart of the capital to the family cemetery on the east side.

Thousands of Lebanese turned out to the same church in June for the funeral of George Hawi, a former Communist Party leader turned critic of Syria's domination of Lebanon, killed by a bomb in his car.

The 48-year-old Tueni was among the most fiery critics of Damascus, publishing his biting editorials on the front-page of his an-Nahar newspaper, Lebanon's leading daily.

Many Lebanese politicians have blamed Syria for Tueni's murder, though Damascus has been quick to deny any involvement.

"Can no one say 'no' in this country without being killed?" asked Druze leader Walid Jumblatt, who campaigned for Syria's withdrawal, in a call to LBC television on Tuesday night.

"I am threatened now ... If what they want is to silence every opposition voice then, then until when?" he said.

Tueni's murder has caused serious political rifts in Lebanon, bringing the government to the verge of collapse.

Five Shi'ite Muslim ministers loyal to Hizbollah and its Amal ally suspended participation in the government after it voted on Monday night to seek a UN inquiry into all the attacks that have rocked Lebanon over the past 14 months.

A Christian minister close to pro-Syrian President Emile Lahoud also walked out of the session, which called for a tribunal with an "international character" to try suspects in the murder of Hariri.

The killing of Hariri and 22 others in a truck bombing in Beirut sparked massive protests that forced Syria to bow to world pressure and withdraw its troops from its neighbour in April after 29 years.

The head of a UN inquiry into Hariri's assassination told the Security Council on Tuesday that the investigation could take years unless Syria speeds up its cooperation.

Detlev Mehlis has implicated Syrian and Lebanese security officials in the murder and identified six Syrians as suspects.

The Security Council also considered a resolution that France, the United States and Britain are proposing to extend the Hariri probe, which ends on Thursday, for six months.

The draft would expand the commission's mandate "to include investigations on the terrorist attacks perpetrated in Lebanon since Oct 1, 2004 at the discretion of the commission."