The violence broke out late on Sunday when the army entered the Sunni stronghold with the aim of arresting wanted militants.

"One soldier was killed and several others wounded" when the unit was targeted by militants, the army said, adding that hand grenades were used against its men.

The army said "one terrorist" was killed and his brother arrested. Weapons and ammunition were also seized.

Lebanon's second city has been directly affected by the violence raging in neighbouring Syria, where the regime of President Bashar al-Assad, who is from the Alawite minority, has been battling mostly Sunni groups since 2011.

Recurring clashes pitting residents from Bab al-Tabbaneh against those of Jabal Mohsen, an adjacent and mostly Alawite neighbourhood, led the army to deploy in the area in 2014.