Lebanon's military forces battling followers of a hard-line Sunni Muslim cleric closed in Monday on the mosque where they are taking cover in a southern coastal city, the national news agency said. It said a total of 12 soldiers had been killed since fighting erupted a day earlier.
The clashes in Sidon, 40 kilometers (25 miles) south of Beirut, is the latest bout of violence in Lebanon linked to the conflict in neighboring Syria. It is the bloodiest yet involving the army. At least three of those killed are officers.
The National News Agency said the clashes also left fifty wounded. The report said it was not clear how many gunmen were killed or wounded in the clashes, nor whether there were civilian casualties.
The heavy fighting with machine guns and rocket-propelled grenades has caused panic among residents of Sidon, Lebanon's third largest city, which until recently had been largely spared the violence hitting other areas.
The city streets appeared largely deserted on Monday, and local media reported many residents were asking for evacuation from the area of the fighting, a heavily populated neighbourhood in the city. The news agency said a government building was hit. The local municipality said that the city is "a war zone," appealing for a cease-fire to evacuate the civilians and wounded in the area.
Many people living on high floors came down or fled to safer areas, while others were seen running away from fighting areas carrying children. Others remained locked up in their homes or shops, fearing getting caught in the crossfire. Gray smoke billowed over parts of the city.
The fighting broke out on Sunday in the predominantly Sunni city. The army says supporters of Sheik Ahmad al-Assir opened fire without provocation on an army checkpoint. It tied the attack to the war in neighboring Syria. Al-Assir is a virulent critic of the powerful Shiite militant Hezbollah group, which along with its allies dominates Lebanon's government. He supports rebels fighting to oust Syria's President Bashar Assad.
Early Monday, al-Assir appealed to his supporters through his Twitter account in other parts of Lebanon to rise to his help, threatening to widen the scale of clashes.
The tweets did not give a clear statement on how the battle began. It came after a series of incidents pitting the cleric's followers against other groups in the town, including Hezbollah supporters and the army.
Fighting also broke out in Ein el-Hilweh, a Palestinian refugee camp near Sidon, where al-Assir has supporters. Islamist factions inside the camp lobbed mortars at military checkpoints around the camp.
Sectarian clashes in Lebanon tied to the Syrian conflict have intensified in recent weeks, especially Hezbollah sent fighters to support Assad's forces. Most of the rebels fighting to topple Assad are from Syria's Sunni majority, while the president belongs to the Alawite sect, an offshoot of Shiite Islam.
Clashes in Lebanon have also mostly pitted Sunni against Shiite. The most frequent outbreaks have involved rival neighborhoods in the northern port city of Tripoli, close to the Syrian border.
The clashes in Sidon centered on the Bilal bin Rabbah Mosque, where al-Assir preaches. The cleric is believed to have hundreds of armed supporters in Sidon involved in the fighting. Dozens of al-Assir's gunmen also partially shut down the main highway linking south Lebanon with Beirut. On Monday, they opened fire in other parts of the city, with local media reporting gunshots in the city's market.
By Sunday evening, the army had laid siege to the mosque, sealing off access to it from all directions.
The military openly linked the clashes of Sidon to the conflict in Syria said in a statement Sunday. It said the attacks on its forces by al-Assir supporters were unprovoked, and accusing the cleric of seeking to "incite strife" in Lebanon. The military vowed to hit back with an "iron fist."
President Michel Suleiman called for an emergency security meeting later Monday.