BEIRUT, (Reuters) – The Arab League won vital Syrian support on Monday for its efforts to end a standoff between Lebanon’s pro-Western government and a Hezbollah-led opposition rallying hundreds of thousands in central Beirut, an envoy said.

Arab League envoy Mustafa Osman Ismail said he also had backing in principle from rival factions in Lebanon.

There should, he said, be “no victor and no vanquished”. “I have received confirmation from the brothers in Syria that they (support)… Lebanese consensus and support our efforts,” Ismail, a Sudanese presidential adviser, said after talks with President Bashar al-Assad in Damascus.

Ismail later travelled to Beirut and began separate talks with rival Lebanese leaders. Arab League Secretary-General Amr Moussa was due to join him in the Lebanese capital on Tuesday.

Syria’s backing is seen as essential in forging any compromise in Lebanon. Though its troops left the country more than 18 months ago, Damascus still wields influence on many groups, the most powerful of which is the pro-Syrian Hezbollah.

An anti-government protest campaign entered its 11th day on Monday with thousands of opposition supporters maintaining a round-the-clock vigil at a tent city in central Beirut.

Hundreds of thousands of protesters attended a rally in Beirut on Sunday to press demands for a national unity government that grants more power to Shi’ite Muslim Hezbollah and its Christian and Muslim allies.

One security force source estimated the rally was the biggest in Lebanese history.

Western-backed Prime Minister Fouad Siniora and his anti-Syrian allies refuse opposition demands, saying Hezbollah wants to place Lebanon under the tutelage of Syria and Iran.

Ismail had told Arabiya television that the proposals cover a unity government, passage of a U.N.-proposed international tribunal to try suspects in last year’s killing of ex-premier Rafik al-Hariri and early presidential and general elections.

Lebanese political sources said Ismail and Moussa faced a difficult task in getting all parties not just to agree on the various issues but also on the sequence of implementing them.

Hezbollah accuses Siniora and some allies of trying to weaken the group during a war with Israel in July and August.

Siniora has accused Hezbollah of trying to stage a coup following the war and commentators have warned the worsening standoff could degenerate into sectarian violence in a country still trying to rebuild after a 1975-90 civil war.

Whereas the last civil war started out primarily as a fight between Christian and Muslim militia, the main faultline now lies between Lebanon’s Sunni community and the Shi’ites.

One Shi’ite protester has been killed and several people hurt in shooting incidents, riots and clashes between supporters of both sides over the past week.