BEIRUT,(Reuters) – Lebanon’s army deployed more soldiers in Beirut on Monday after the killing of a pro-Syrian Shi’ite Muslim demonstrator raised fears anti-government protests could turn into sectarian violence.

Arab League Secretary-General Amr Moussa warned the crisis could worsen and indicated he had discussed ideas for a solution with Lebanese officials during a 24-hour visit to Beirut.

Security sources said the military increased its forces in Sunni districts that Shi’ite protesters drive through to get to central Beirut where the Hezbollah-led opposition is holding a sit-in to topple the Western-backed government.

These districts witnessed several clashes between residents and protesters on Sunday — from stone-throwing to fights with sticks and knives.

In the most serious incident, gunmen fired from assault rifles at a group of protesters in the Sunni Qasqas neighbourhood, a stronghold for the anti-Syrian majority coalition, killing one man and wounding others.

The opposition said the incidents would not make it abandon plans for toppling the government. It will hold a mass funeral for the killed man on Tuesday. “The leadership is aware and wise and it can forgive this incident. It will happen again but we won’t be dragged into this (sectarian) issue because it’s a dirty game,” protester Mohammed Atweh, 30, told Reuters in central Beirut.

Many politicians and observers had said the crisis could spill over into sectarian strife in a country that had gone through two civil wars in the last century.

Lebanon’s most senior Shi’ite cleric Grand Ayatollah Mohammad Hussein Fadlallah called for unity in the face of attempts to drag the country into civil strife. “One of the most dangerous things is the devilish state of sectarian instigation by some political symbols… which is making the political dispute open to sectarian sensitivities,” Fadlallah said on Monday.

Moussa, who met Lebanese leaders including Hezbollah officials, said before he left Beirut: “The whole Arab arena can’t stand by and watch a situation that could develop to the worse”. Asked for details about his efforts, he said: “It is still at its beginnings but I see that it is a start that gives some hope.”

The Shi’ite group Hezbollah, which is backed by Syria and Iran, and its allies in the opposition had taken to the streets and were holding an indefinite sit-in to force the resignation of Western-backed Sunni Prime Minister Fouad Siniora.

Thousands of protesters spent a third night in a newly built tent city in central Beirut outside the main government complex where Siniora was spending his days and nights.

Many banks and businesses were closed on Monday in the downtown area, Lebanon’s banking and commercial centre. Business owners in the area have said that lengthy closures could devastate several businesses and force employers to cut jobs.

The opposition, which includes some Christians, has been demanding effective veto power in the government, which has a majority comprising of anti-Syrian politicians from Christian, Sunni and Druze parties. But these politicians say the opposition only wants to weaken the government and derail a U.N. tribunal that would try suspects in the 2005 murder of ex-premier Rafik al-Hariri.

A preliminary U.N. inquiry has implicated Syrian and Lebanese security officials in the killing, which led to Syrian forces being forced to withdraw from Lebanon last year.

German Foreign Minister Frank-Walter Steinmeier arrived in Syria on Monday on a visit to urge President Bashar al-Assad to play an active role in helping stabilise the Middle East.