Lebanese officials said Syrian troops deployed in Damur village just south of Beirut and Aramun to the east began withdrawing towards the eastern Bekaa Valley on Tuesday.
They said Syrian forces would at a later stage redeploy troops from northern and central areas towards the Bekaa.
Earlier, a senior Syrian military delegation was holding talks with Lebanese army commanders on Tuesday to give the signal for a major Syrian troop movement.
It comes 19 days after the UN Security Council adopted a resolution demanding Syria withdraw its forces from Lebanon and stop interfering in its neighbour's internal affairs.
"The meeting aims to discuss the application of the Syrian army redeployment which comes in the context of continuous coordination between the Lebanese and Syrian leadership as stated by the political resolution agreed to by both presidents," Rafiq Shlala, the media adviser to Lebanese President Emile Lahud, told Aljazeera.
The Syrian contingent is headed by Defence Minister Hasan Turkmani and the Lebanese by army Commander Michele Sulayman.
"Regional details are also being discussed," Shlala added.
Redeployment of Syrian soldiers
has taken place before
"Available information is that the deployment will include Syrian military units based at sites on the mountain and in the north, towards the al-Biqa area, according to the al-Taif agreement applied in Lebanon since 1990."
He said the redeployment was the fifth. The first was carried out in June 2001.
Lebanese forces were expected to take over the evacuated positions, sources said.
Asked about reports on Lebanese fears of a US-Syrian deal against Lebanon, Shlala said "the Syrian-Lebanese relationship has reached high levels of coordination and cooperation" and could not fall victim to a bargain.
"There is a mutual strategy in place between the two leadership, there are national standards stating the relationship," he said.
The United States and France drafted Security Council Resolution 1559 after Syria, which has about 17,000 troops in Lebanon, asked top officials in Lebanon to extend the mandate of its close ally President Emile Lahud despite local opposition.
The Lebanese parliament brushed aside the resolution, which also called for foreign armies to leave Lebanon and amended the constitution to allow Lahud to serve three more years.
UN Secretary General Kofi Annan is expected to report to the Security Council on compliance with the resolution by 2 October.