Under pouring rain, a convoy of 200 armored vehicles towing cannons and rocket launchers, T-52 and T72 tanks, military trucks and buses carrying more than 500 soldiers were seen heading to the Masnaa border point.
There are about 500 Syrian soldiers left in Lebanon, a senior Lebanese military officer said.
"All Syrian troops will leave Lebanon by Tuesday," the officer told The Associated Press, speaking on condition of anonymity, as is typical for military officials here.
An Associated Press reporter in the city of Baalbek in the eastern Bekaa Valley said the accelerated Syrian troop withdrawal Saturday night was delayed for a few hours by a heavy downpour, unusual for this time of year.
At their last major garrison in Lebanon, the Bekaa town of Deir el-Ahmar, Syrian soldiers burned documents, dismantled military posts and loaded ammunition on to trucks.
Syrian intelligence agents vacated their headquarters in Baalbek at noon Sunday and later the Lebanese army moved in and took over the position. Lebanese soldiers also hoisted the Lebanese flag at a vacated Syrian checkpoint in Deir el-Ahmar. A Lebanese bulldozer filled holes and trenches used by retreating Syrian soldiers in Baalbek.
With the latest Syrian pullout, the Bekaa Valley has become almost entirely clear of Syrian troops and military intelligence, witnesses said. The exception is the border town of Anjar, home of Syria's chief of military intelligence in Lebanon, where Syrian officials appeared to be going about their business as usual Sunday.
Syrian and Lebanese officials said Sunday that Syria was withdrawing all but a token force that will remain in Lebanon for a farewell ceremony Tuesday that the Lebanese Army plans to hold in a town near the border.