Palestinian leaders are striving to ensure that fighting between army troops and Islamist militants in north Lebanon does not ignite violence at refugee camps elsewhere.
Palestinian factions at the sprawling Ain al-Hilweh camp in south Lebanon said they were determined to prevent any spillover from nearly two weeks of clashes pitting the Lebanese army against Al- Qaeda-inspired fighters at Nahr al-Bared camp.
The Fatah al-Islam group -- which the Lebanese government says has many Arab foreigners in its ranks -- has little support among Palestinians, but army bombardment of Nahr al-Bared over the past 13 days has stirred fear and resentment in other camps.
"Palestinian forces have all decided that the battles will not be transferred to Ain al-Hilweh and to tighten security in the camps," said Muneer al-Maqdah, a Fatah military commander.
Ain al-Hilweh, home to about 70,000 refugees, is the biggest of Lebanon's 12 camps. They house 400,000 Palestinians whose families fled the conflict over Israel's creation in 1948.
Dilapidated and squalid, the unruly settlements have few health and social services. Refugees are banned from working in more than 70 professions in Lebanon, so unemployment is high.
A 1969 Arab agreement barred Lebanese security forces from the camps, which were to be policed by Palestine Liberation Organisation guerrillas then setting up bases in Lebanon.
Israel's 1982 invasion of Lebanon forced out most of the guerrillas and heavy weaponry, leaving the camps in the hands of competing factions which are still allowed to keep their guns.
Beyond the reach of the Lebanese authorities, the camps also provide sanctuary for Islamist militants and wanted criminals.
The army has so far held back from storming Nahr al-Bared -- a risky act that would breach the 1969 Cairo agreement and could cause heavy civilian casualties. Such an assault might also spur militants in other camps to retaliate against the army.
Such groups are known to have a presence in Ain al-Hilweh, near the southern port of Sidon, where they are distrusted both by Fatah, the biggest faction, and its Islamist Hamas rival.
"There are elements that are not under any umbrella, neither Islamist nor nationalist. If things get worse (in Nahr al-Bared) they might attack the army," said Abu Ahmed Fadel Taha, Hamas's representative in Sidon. "They can throw a grenade or a bomb."
He said mainstream factions had so far been able to keep a lid on rogue militants, but they remained worried about them.
Fatah leaders, however, insisted such groups were small, were under control and posed no threat to camp security.
Periodic skirmishes have shaken Ain al-Hilweh in recent months, mainly between Fatah and a small, Sunni Muslim militant group called Jund al-Sham. Most have been swiftly contained.
Security sources say Jund al-Sham has only a few dozen combatants, some of whom have fought in Iraq.
Usbat al-Ansar, a bigger Islamist militant group based in Ain al-Hilweh, says it is helping to keep Jund al-Sham under control in return for protecting the group from its rivals.
"They realise their numbers are very small, their weaponry is very little. If Usbat al-Ansar lifts its cover off them, they wouldn't exist," said Usbat al-Ansar spokesman Abu Sharif.
The Nahr al-Bared fighting has yet to spread elsewhere, but Ain al-Hilweh residents said they felt the tension.
"Of course we're scared that something will happen here because all the camps are threatened. The army could decide to battle militants here," said Sawsan Majzoub, 28.