Tensions continued  in the southern Lebanese city of Sidon on Monday, a day after three people were killed and seven injured in clashes between followers of Sunni Muslim cleric Sheikh Ahmed al-Aseer and supporters of the militant Shi'ite movement Hezbollah.

Streets were deserted and schools across the port city closed, as the Lebanese army was deployed to the area.

"Army troops have received clear orders from their command to open fire on any gunman," Interior Minister Marwan Charbel said.

The clashes occurred in the Tameer area, on the outskirts of Sidon, when followers of al-Aseer began removing banners hung by Hezbollah to mark Ashoura, a 10-day Shi'ite religious ceremony.

"It will be over my dead body if Hezbollah is allowed to erect one banner from now on in our area. We will not keep silent on the blood that was shed on Sunday," al-Aseer was quoted in the local media as saying.

Al-Assir has repeatedly criticized Hezbollah for backing the regime of Syrian President Bashar Assad. Many Sunnis in Lebanon back the Sunni-led rebellion against Assad.

The violence in neighboring Syria has in recent months spilled several times into Lebanon, with opponents and supporters of Assad clashing in the northern city of Tripoli.