BEIRUT: Ten fighters from Lebanon’s Shiite Hezbollah group were killed in clashes with fighters from Al-Qaeda’s Syrian wing in eastern Lebanon on Sunday, a source close to the group said on Monday. The death toll was one of the highest the group has suffered in a single action since it said it would fight alongside the forces of Syrian President Bashar Assad.

The move by Iran-backed Hezbollah, announced last year, has helped turn the tide of civil war in Syria against insurgents seeking to oust Assad. Hezbollah pushed back a major offensive on Sunday by hundreds of fighters from the Nusra Front who attacked several bases of the group along a mountainous range close to the border, the latest spillover of violence from Syria’s civil war. Sources said dozens of Nusra fighters were also killed.

Sunday’s two-hour battle in the mountains of the Shiite village of Britel, in which both sides used mortars and rocket-propelled grenades, is one of the deadliest fought in Lebanon between the Shiite group and Syrian insurgents.