In what observers say is the worst fighting to hit Tripoli in two decades, army tanks opened fire on positions inside Nahr al-Bared camp held by militants from Fatah Islam, a Sunni al-Qaeda-styled group. The group's presence spurred the army to close public access to the camp earlier this year, devastating local incomes.
After suffering its heaviest losses in many years, security analysts predict the Lebanese army may increase its military presence around all Palestinian refugee camps, home to over half of Lebanon's more than 400,000 Palestinian refugees, further limiting public access and damaging an already fragile economic and social environment.
"The Lebanese army will be shocked by this as they have not normally considered themselves a target for attack," Timor Goksel, a former United Nations Interim Force in Lebanon (UNIFIL) spokesman and long-time Lebanon security analyst, told IRIN.
"The army plays a very important internal security function and they will now need to restore their credibility. The army might consider putting camps across Lebanon under a similar kind of siege and all Palestinians could suffer. There might be more bloodshed," he added.
Under a decades-old agreement with Lebanon, internal security in the camps is left to the Palestinians, predominantly the Fatah party, which is the largest faction and a secular rival to the less popular Fatah Islam.
Bank robbery triggers violence
Sunday's violence began shortly after dawn when police raided a militant-occupied apartment on a major thoroughfare in Tripoli. Authorities said police were looking for suspects of a bank robbery a day earlier in Amyoun, a town southeast of Tripoli, in which gunmen made off with US $125,000 in cash. Local media reported the gunmen to be members of Fatah Islam.
The armed militants resisted arrest and a gun battle ensued. It spread to surrounding streets and continued through the afternoon.
Witnesses said Fatah Islam militants then seized the lightly defended Lebanese army checkpoints at the entrance to Nahr al-Bared, capturing two armoured carriers. The gunmen also opened fire on roads leading to the city and ambushed a military unit travelling through Koura, killing four soldiers, security officials said.
Smoke billowed from the camp as a steady barrage of artillery and heavy machine gun fire from army positions pounded militant positions inside the refugee camp. Palestinian sources inside the camp said a least a dozen civilians had been wounded in the fighting.
Abu Saleem Taher, spokesman for Fatah Islam, told IRIN from inside the camp that militants from the group had attacked the army in retaliation for an incident the previous day in which he claimed Lebanese soldiers had opened fire on Fatah Islam members as they entered the camp. The army was not immediately available for comment on the allegation.
"God is testing us"
"God is testing us and we will serve his cause," said Taher. "We are ready to continue our fight against the Lebanese army and we know that our brothers in the other camps will not stand still if the situation continues."
As he spoke, the sounds of gunfire and heavy artillery could be heard in what are continuing clashes between soldiers and militants around the edge of the camp.
Security in and around Lebanon's 12 Palestinian refugee camps, which are off-limits to the authorities, has been breaking down steadily over the past month, with deadly gun battles between rival militants in Ayn al-Helway, the largest and most lawless of the camps, near the southern port city of Sidon.
"We are really afraid about what is happening and we don't want these people in our camp," Abu Raheja, a Nahr al-Bared shopkeeper, told IRIN. "Fatah Islam is not letting the wounded and civilians leave the camp. They are using us as human bullet vests," he said.
Lebanon's leaders appealed for calm, denouncing Fatah Islam. Saad Hariri, leader of the Sunni-dominated parliament, called on the people of Tripoli to cooperate with the Lebanese army. "Everyone knows these terrorists are criminals and have no relation to Islam," he told LBC Television.
Syria's Interior Ministry said it had closed two border crossings from north Lebanon at Arydha and Daboussyah in response to the clashes.