Hundreds of thousands of pro-Syrian demonstrators are rallying in the Lebanese capital to denounce what they are calling Western interference in Lebanon's internal affairs.

The demonstration, called by the Syrian-backed Shi'ite militant group Hezbollah, gridlocked central Beirut -- the site of near-daily anti-Syrian protests that began after last month's assassination of former Lebanese Prime Minister Rafik Hariri.

Hezbollah chief Hassan Nasrallah says Tuesday's rally is aimed at thanking Damascus for what he called Syrian sacrifices in Lebanon.

Hours after the protests began, the first of Syria's estimated 14,000 troops in Lebanon began evacuating coastal and central areas to positions near the Syrian border.

Syrian President Bashar al-Assad and his Lebanese counterpart, Emile Lahoud, announced the pullback Monday, after weeks of pressure from the United States, the European Union and several Arab governments.

The two leaders said the redeployment to Lebanon's Bekaa Valley will be completed by the end of the month, ahead of talks on a timetable for a full Syrian withdrawal.