NICOSIA — Syria has launched its largest military operation yet along the border of Lebanon in search for Sunni insurgents.

More than 5,000 Syrian troops, supported by main battle tanks, stormed the border with Lebanon in an operation against defectors. Officials said the Syrian Army force bombarded the northern Lebanese resort of Zabadani, regarded as a waystation for weapons smuggling to fuel the revolt against President Bashar Assad.

The operation began on Oct. 15, and casualties among the Syrian Army were said to be high. Officials said Russian-origin T-72 MBTs and BMP infantry fighting vehicles launched barrages of shells and anti-aircraft weapons in the mountains along the Lebanese border.

Officials said the army conducted house-to-house searches in Zabadani and arrested more than 150 people. They said infantry units were led by Military Intelligence, which contained names of suspected defectors who joined the opposition to Assad.

The army operation was said to have met stiff resistance. Syria opposition sources said hundreds of Sunni Muslim defectors fought gun battles with Assad forces, with many of them believed to have escaped to Lebanon.

Over the last three months, the Assad regime has determined that the 330-kilometer border with Lebanon was being used for weapons smuggling to the Syrian opposition. The Lebanese border, repeatedly infiltrated by Syrian troops, contains at least 50 unauthorized crossing points.

On Oct. 14, the Lebanese Army reported the capture of a weapons delivery toward Syria about 140 kilometers north of Beirut. The weapons cache was said to have contained automatic weapons and rocket-propelled launchers.

Officials said the Sunni community in Lebanon, including those around former Lebanese Prime Minister Said Hariri, was believed to be financing the weapons smuggling to Syria. Hariri has denied any involvement and said Alawites were the leading consumers of illegal weapons.

The Assad regime has sought to coordinate border security with the Lebanese government. In mid-October, army commanders from both countries discussed measures to block arms smuggling.

  000 troops with tanks against defector forces on Lebanon border, Bashar Assad, Syrian Army sends 5