Updated

Tens of thousands marched Monday in the biggest anti-Syrian protest in Lebanese history amid signals that Syria (search) will soon withdraw its troops from parts of the country. President Bush renewed demands for Syrian forces to leave Lebanon immediately.

The protest marked one week since the Feb. 14 death of Rafik Hariri (search) and began at the bomb-scarred site of the former prime minister's assassination, which turned many Lebanese against Syria and increased international pressure on Damascus to extract its army from Lebanon (search).

Holding aloft red roses and Lebanese flags, the throngs on the streets shouted insults at Syria and demanded the resignation of the pro-Syrian government in a march that began at the seaside site where Hariri and 16 others were killed and ended at his grave in the city center.

The protesters wore scarves of red and white — the colors of Lebanon's flag — which have become the symbol of the opposition's "independence uprising," described as a peaceful campaign to dislodge the government and force the Syrian army out of Lebanon.

Hariri's assassination has brought Lebanese together and strengthened the opposition, but it was unclear if the momentum would force a change in government or push the Syrian army out of the country.

Another former prime minister Gen. Michel Aoun, said Monday he would return from exile before this year's parliamentary elections and that he may launch his own candidacy if the opposition needs his support. The former commander of the Lebanese army fled the country in 1990.

"I will return before the legislative elections, probably by mid-April," Aoun told The Associated Press in a telephone interview from Paris. "And if the situation is critical for the opposition in a region, then I will throw in my personal weight and run in the elections."

As the demonstration was under way in Beirut, Bush issued a strong warning to Syria from Brussels, saying Damascus "must end its occupation of Lebanon."

In Damascus, Arab League Secretary-General Amr Moussa said Syrian President Bashar Assad affirmed during a meeting that his country will "soon" take steps to withdraw its army from Lebanese areas in line with a 1989 agreement. It was not clear whether that meant Syria would completely leave Lebanon.

Syria, which sent its army into Lebanon in 1976 amid the bloody civil war, has always pledged to implement the 1989 accord that ended the conflict, and has redeployed troops several times since 2000. However, a withdrawal to the eastern Bekaa Valley near the border that was scheduled for the early 1990s, followed by an eventual total pullout, has never been carried out.

Syrian troops here once numbered 35,000; the current number is 15,000, and Syria remains the chief power broker in Lebanon. Syrian Foreign Minister Farouk al-Sharaa said recently he expects Syrian troops to stay for two more years.

Demonstrators in Beirut beat drums and held up portraits of leaders assassinated during the 1975-90 civil war as they sang patriotic songs. Shouts of "Syria out!" and "Syria is the criminal," competed with loud insults directed against the Syrian president — words that until few months ago few dared to say in public.

Marching past policemen and army troops in full battle gear, some carried banners reading, "Independence," and chanted, "The government of puppets must fall" and "Enough blood, leave us alone." Playing on words, one placard read in English: "Syrial killers."

In a show of Muslim-Christian national unity, some protesters held a copy of the Quran in one hand and a cross in another.

"Enough bloodshed and disasters. It is the 21st century, and people should be able to govern themselves," said Youssef Mukhtar, a 47-year-old Lebanese-American engineer. "The situation has become unbearable and we have to regain our country."

Salma Raya, a 25-year-old student waving a Lebanese flag, said: "We want the Syrians out. We want our independence. What are we waiting for?"

Many in Lebanon blame Syria for a string of political assassinations during and after the civil war, including those of the Druse leader Kamal Jumblatt and Lebanese President-elect Bashir Gemayel.

On Monday, pro-Syrian President Emile Lahoud said "Israel was the first to benefit" from the assassination of Hariri, a Lahoud rival best known as the man who negotiated the 1989 accord and rebuilt Lebanon while serving as prime minister during 10 of the 14 years after the conflict.

European Union foreign ministers on Monday demanded an international investigation into the assassination, joining France, the United States, the Lebanese opposition and the Hariri family. The Lebanese government has said it will cooperate with a team to be sent by the United Nations but will not allow an international inquiry.

The killing of Hariri, a Sunni Muslim, shook Lebanon and sparked an outpouring of sympathy that cut across the sectarian divide. His funeral Wednesday turned into mass demonstration against Syria's control of Lebanon.

Monday's crowd was estimated in the tens of thousands — the largest anti-Syrian demonstration ever in Lebanon. A Nov. 30 demonstration called for by the pro-Syrian government to counter the opposition drew some 100,000 people.

Prime Minister Omar Karami's government last week extended a hand to the opposition, calling for dialogue.

The protesters observed a moment of silence at 12:55 p.m., the exact time that Hariri's motorcade was blown up.