The Lebanese news agency says military forces battling followers of a hard-line Sunni cleric are closing in the mosque where they are taking cover in a southern coastal city. It says the fighting brought the death toll to 12 soldiers.
The clashes in Sidon are one of the most intense bouts of violence in Lebanon linked to the conflict in neighbouring Syria.
The National News Agency said clashes continued into Monday morning, also leaving fifty wounded. The report said it was not clear how many gunmen were killed or wounded in the clashes and whether there were any civilian casualties.
Sheikh Ahmad al-Assir supports rebels fighting to oust Syria's President Bashar al-Assad.