The leaders of Syria and Saudi Arabia launched an unprecedented effort on Friday to defuse fears of violence over upcoming indictments in the 2005 assassination of former Lebanese Prime Minister Rafik Hariri.
Lebanese Prime Minister Saad Hariri - the son of the slain statesman - met with Saudi King Abdullah at Hariri's residence in Beirut.
Earlier on Friday the two leaders, as well as Lebanese President Michel Suleiman met with Syrian President Bashar Assad.
It was a strong public show of cooperation between Saudi Arabia and Syria, which for years vied for influence over Lebanon.
Following the meetings, Abdullah and Assad departed for their respective homelands, and shortly afterwards Qatari Emir Sheikh Hamad bin Khalifa al-Thani arrived for talks with the Lebanese leadership.
Many fear that new violence between Lebanon's Shiite and Sunni communities could break out if the international tribunal investigating Hariri's death implicates the Shiite militant group Hezbollah, which is Syria's main ally in Lebanon.
In May 2008, Hezbollah gunmen swept through Sunni pro-government neighbourhoods of Beirut, raising fears the country could fall into a new civil war.
That crisis was resolved only after fellow Arab countries mediated a truce and political compromise between the two sides that has tenuously held since.
Hariri was a Sunni leader with strong links to Saudi Arabia.
The international tribunal investigating Hariri's death has not announced who will be charged, but the leader of Hezbollah said last week members of his group will be among those indicted.
The summit was unusual on multiple levels, a sign of the depth of concern over the potential for violence.
Assad rarely goes to Beirut - his last trip was in 2002, which at the time was the first visit by a Syrian leader to the Lebanese capital in nearly three decades.
Many in Lebanon blame Syria for the truck bombing on Valentine's Day 2005 that killed Hariri, charges that Damascus denies.
The blast deepened a rift between Assad and Saudi King Abdullah, who each backed rival sides in the ensuing power struggle that nearly tore Lebanon apart since 2005: Syria backing a Hezbollah-led coalition and Saudi Arabia and the United States supporting a Sunni-led coalition.
In recent years, however, Assad and Abdullah have repaired ties, and the joint visit was a sign of how far the rift has healed.
No details were released about Friday's one-day summit, although Hezbollah Cabinet ministers were also expected to take part.
Another factor behind the summit may be worries that any turmoil within Lebanon could expand into conflict with Israel, which fought a 2006 war with Hezbollah.
Hezbollah leader Hassan Nasrallah's announcement that his militia members would be implicated in Hariri's slaying appeared to be an attempt to undercut the repercussions of any indictment, and he dismissed the international tribunal as an "Israeli plot."
Hezbollah said it supports Friday's summit.
Hezbollah has immediate concerns that go beyond the tribunal, however, sparked by reports that Syria sent Scud missiles to Hezbollah and suspicions that Hezbollah patron Iran wants to acquire nuclear weapons. Syria denies sending Scuds.
Hariri's death sparked massive anti-Syrian protests in Lebanon, dubbed the "Cedar Revolution," helping lead to the withdrawal of Syrian troops from Lebanon in 2005, ending almost three decades of Syrian domination.