Despite the assurance from the United Nations, protests raged on in Lebanon.
In meeting with Annan on the sidelines of an Arab summit in Algiers, Syrian President Bashar Assad agreed to present a firm timetable by early April for a full withdrawal of his country's forces from Lebanon.
Assad confirmed his commitment to U.N. Resolution 1559, which calls for a Syrian withdrawal.
"The withdrawal has begun and it continues. He's working out a timetable in consultation with the Lebanese authorities and will withdraw his troops completely into Syrian territory. Not just the troops but also the security service, as well as all the logistical and material equipment to Syria," Annan told reporters.
Syria has pulled back its troops and intelligence agents into eastern Lebanon toward the border and has been promising to work out their complete removal with the pro-Syrian government in Beirut. But it has so far not given a timetable, despite mounting international pressure on it to get out of the nation it has dominated for years.
Annan said Assad agreed a timetable would be ready in time for a visit to Damascus by a U.N. envoy in the first week of April. Annan said he expects the envoy to return with a "credible and well-defined timetable."
"We need to see all of them withdrawn and President Assad has confirmed to me that that is his intention and he will implement 1559 in full," said Annan. "We are going to work with him to ensure that it is done."
In the pullback over recent weeks, Syria says 4,000 of its 10,000 troops left Lebanon completely. The remainder are in the Bekaa Valley in eastern Lebanon.
The United States, France and the United Nations have stepped up pressure on Syria to get out of Lebanon before legislative elections, expected to be held before the legislature's current term expired at the end of May. Key Arab states — Saudi Arabia and Egypt, in particular — have pressed Syria to comply.
Syria sent troops to its smaller neighbor in 1976, ostensibly to the keep the peace during a civil war. But they stayed on after the war ended in 1990, helping Syria keep a grip on Lebanese political affairs.
Meanwhile, protests continued in Lebanon, as roughly 1,000 students shouting "Death to America!" and shredding a portrait of President Bush marched on the U.S. Embassy in Beirut on Tuesday to criticize what they said was Washington's interference in their country's decisions.
A newspaper owned by slain former premier Rafik Hariri said a U.N. team investigating his Feb. 14 assassination is expected to accuse Lebanese authorities of negligence and evidence tampering.
The demonstrators, mostly supporters of the militant group Hezbollah, also shouted "Death to Israel!" and waved Lebanese flags as they tried to push through barbed wire and a Lebanese army checkpoint. It was the second anti-U.S. protest in eight days organized by student groups backing the pro-Syrian government.
Hariri's Feb. 14 assassination sparked unprecedented anti-Syrian protests that led Prime Minister Omar Karami to dissolve his government and brought intense international pressure on Syria to completely withdraw its army from Lebanon. Damascus withdrew troops to eastern Lebanon earlier this month and has promised a total pullback.
Both sides are competing on the street to show they have the most public support.
On March 15, hundreds of thousands of anti-Syrian demonstrators flooded the capital in the biggest protest ever in Lebanon.
Hezbollah also has organized large demonstrations. Its March 8 rally drew a half-million people in a sign of its determination to ensure no future Lebanese government would consider peace with Israel or pressure the militant group to disarm.
The demonstrators on Tuesday did not get close to the fortified embassy. Lebanese soldiers, riot police and barbed wire stopped them about a half-mile away.
The U.S. government blames the pro-Iranian Hezbollah for the 1983 bombing of its Beirut embassy which killed 63 people, 17 of them Americans.
On Tuesday, protesters called for the U.S. ambassador's expulsion and tore a portrait of Bush, who has repeatedly called on Syria to remove its troops and intelligence agents from Lebanon.
Speakers voiced support for Hezbollah's resistance against Israel, saying they rejected disarmament of the guerrilla group as called for in a U.N. resolution.