Arab diplomats are struggling to bridge differences between Lebanon's government and the Hezbollah-led opposition.
Arab League Secretary General Amr Moussa arrived in Beirut Tuesday for meetings with both sides. He said he has ideas about resolving the standoff.
An Arab League envoy, Mustafa Ismail of Sudan, met with Syrian officials in Damascus and the parties in Lebanon on Monday.
Thousands of Hezbollah supporters have been camping out in central Beirut since December 1, demanding that the Western-backed government of Prime Minister Fuad Siniora step down.
The demonstrators are pressing demands for a national unity government that grants more power to pro-Syrian Hezbollah and the Shi'ite militant group's allies.
Mr. Siniora's government Tuesday agreed to refer to parliament a United Nations plan for an international tribunal to try suspects in the 2005 assassination of former Prime Minister Hafik Hariri - an anti-Syrian politician.
Mr. Siniora's coalition accuses the pro-Syrian opposition of conspiring to scuttle the creation of the tribunal.
In related news, the head of the U.N. probe into the Hariri assassination said in a report released Tuesday that Syria's cooperation has been generally satisfactory.
A previous U.N. investigator, Detlev Mehlis, implicated senior Syrian security officials in the killing.
Some information for this report was provided by AFP and Reuters.