Nearly 17 armed factions and 70,000 people are packed into this teeming Palestinian slum.
Militants patrol narrow passageways that connect cement and cinder-block dwellings overfilled with poor families. For months now they have coped with a violent feud between rival groups that has threatened to spill into an all-out battle similar to last year's conflict in Nahr al-Bared refugee camp in northern Lebanon.
But the groups – secular, leftist, Islamist, nationalist, jihadist – are attempting to forge a rare pact to bring about a much-needed reprieve to tensions in Ein el-Hilweh, which has caused even the more radical, Al Qaeda-inspired elements to publicly moderate their views. The pact could see the formation of a joint security force to police the camp.
The restraint comes as Lebanon and Syria are paying closer attention to the potential threat posed by jihadists after recent bomb attacks in both countries. And groups such as Esbat al-Ansar, which the US considers a terrorist organization, are mindful of the outcome of the fight in Nahr al-Bared when the Lebanese Army took on the Al Qaeda-inspired militants of Fatah al-Islam. The camp was flattened, more than 200 militants were killed, and 30,000 residents were left homeless.
"After Nahr al-Bared, it seems that the same story is coming to Ein el-Hilweh," says Sheikh Ali al-Yussef, an influential Palestinian cleric based in the south Lebanon town of Sidon who helped mediate between the Lebanese Army and Fatah al-Islam during last year's conflict. "It is the decision of all Islamic forces in Ein el-Hilweh to avoid another Nahr al-Bared."
The moderation currently displayed by Esbat al-Ansar – and the closely linked Harakat Islamiyya Mujahidda (Islamic Strugglers Movement) – appears to be a gesture of pragmatism rather than a fundamental shift away from their ideological beliefs.
"They are showing the same pragmatism as other Islamist groups that have moved from radicalism to a more mainstream approach," says Omayma Abdel-Latif of the Carnegie Endowment's Middle East Center in Beirut.
Esbat al-Ansar consists of some 200 militants – many veterans of Afghanistan, Chechnya, and Iraq. They are responsible for a string of bombings in the Sidon area against shops selling alcohol, and members of the group gunned down four Lebanese judges in 1999 during a session in a Sidon court.
On a recent visit to the camp, members of the group lolled outside their mosque. Some had long hair and thick beards and wore the salwar khameez, the long tunic and baggy trousers common in Afghanistan.
"Esbat al-Ansar have become wiser and have a greater understanding of the situation. They came to the conclusion that they have to change their behavior," says Sheikh Jamal Khattab, the leader of Harakat Islamiyya Mujahidda and the top representative of Islamist forces in Ein el-Hilweh, in a rare interview with a Western reporter.
Diplomatic sources say that Lebanese authorities have offered amnesty to Esbat al-Ansar and other militants for past crimes so long as they moderate their behavior, a deal that apparently has encouraged the transition.
Sheikh Khattab, who holds a degree in business administration from the American University of Beirut and speaks fluent English, smiles often during the conversation. His demeanor is in marked contrast to his reputation as an advocate of the extremist Islam of Al Qaeda.
In the 1980s, his Al-Nour mosque was reportedly a logistics hub for recruits to fight the Soviet occupation of Afghanistan. In 2003, Khattab's group allegedly resumed its earlier role, assisting militants traveling to Iraq. Asked to comment on some of these allegations, Khattab smiles through his salt-and-pepper beard and denies them.
"Why would I care about Afghanistan when our struggle is for Palestine?" he asks. As for Iraq, he says, "Some from Esbat al-Ansar traveled to Iraq. When the resistance turned sectarian in Iraq, the volunteers from Ein el-Hilweh stopped going."
Some jihadists in Ein el-Hilweh, however, reject the new moderation of Esbat al-Ansar.
Confined to a tiny quarter of the camp, they comprise a loose coalition from Jund ash-Sham, a jihadi group formed in 2004 but formally dissolved last year, and remnants of Fatah al-Islam. Some have been indicted for staging attacks against United Nations peacekeepers. Lebanese authorities have no jurisdiction in the Palestinian camps, although Lebanese military intelligence has been playing a greater role in Ein el-Hilweh.
Islamists insist that Jund ash-Sham has been contained and blame secular Fatah, which is riven by an internal power struggle, for stirring up trouble. "We think the problem is with Fatah because it has too many leaders [in the camp] and there is no one in overall control of them," says Sheikh Yussef, the Palestinian cleric.
But "Lino," a prominent Fatah commander, says Fatah prefers a peaceful solution. "All the Palestinian forces are discussing how to get rid of Jund ash-Sham," he says. "If a peaceful solution is not found, we will mount a security operation against them and finish them off once and for all."