As a United Nations convoy went in to deliver much-needed aid to some 40,000 trapped dwellers of the Nahr al-Bared camp, which is used as a cover by Fatah al-Islam militants, several shells exploded near one truck, injuring a few UN workers, Arabic satellite network Al Jazeera said.
At least 80 people have been killed since early Sunday, when fighting between units of the Lebanese Army and members of Fatah al-Islam broke out in the neighboring city of Tripoli.
"There is shortage of food, electricity, and water at Nahr al-Bared," said Ali Baraka, a Hamas official in Lebanon. "People cannot step out of their homes onto the streets because of indiscriminate gunfire."
Lebanese troops surrounded the remaining militants in the northeast of the camp and demanded that peaceful dwellers abandon the area to avoid further collateral casualties.
On Monday, Lebanon's government, infuriated by militant attacks that killed at least 32 soldiers in three days of fighting, ordered the Army to step up its sweeping operation in the camp. The latest reports put civilian deaths at 27 and casualties among Islamist militants at about 20.
"We must put an end to the phenomenon of terrorism," Information Minister Ghazi Aridi said.
Many experts consider members of radical Sunni Fatah al-Islam group to be followers of the global al-Qaeda network.
The group, whose leader Shaker al-Absi has been accused of direct ties with al-Qaeda in Iraq, claimed responsibility for two bombings in Beirut Sunday and Monday, which reportedly killed one woman and injured at least 17 people.
Lebanese authorities are also concerned about the possibility that fighting could spread to other Palestinian refugee camps in the country. There are 12 Palestinian camps in Lebanon that are home to a total of around 400,000 people.
Moscow condemned terrorist acts in Lebanon and urged the Lebanese leadership to prevent a further escalation of violence in a statement Tuesday.
"We resolutely condemn these acts of terrorism and hope that they will meet with an appropriate response," Foreign Ministry spokesman Mikhail Kamynin told a news conference in Moscow.
"We also hope that the government of Lebanon and leading political forces in the country will deal with the current situation rationally, and will not allow it to deteriorate even further," the Russian diplomat said.
