As a truce between the Lebanese military and Islamic militants entered its fourth day, three U.S. transport planes landed in Beirut carrying military aid.
The U.S. transports are part of an international delivery of military supplies, with the others coming from Arab nations.
The planes arrived from Kuwait, The Associated Press reports.
Fighting broke out in Tripoli last Sunday, when Lebanese security officials raided an apartment where members of Fatah Islam -- a militant Islamist group lined to al Qaeda -- were holed up, sparking a gun battle.
The militants eventually made their way to the Nahr el-Bared Palestinian refugee camp where they took over military checkpoints outside the camp as well as positions within.
Thousands of Palestinian refugees have since escaped the compound. The flow continued on Saturday as a few dozen people took advantage of the lull in the fighting to leave the camp. Sporadic shooting continued throughout the day.
There were reports that some were taking the opportunity to get out amid fears the Lebanese military is preparing for a major fight. The army has surrounded the camp with troops, artillery and tanks.
The militants, however, claim to have 500 well-armed fighters ready to do battle.
At least 20 civilians and 30 troops have been killed in the fighting this week. According to the Lebanese military, 60 militant fighters have been killed.
However, Fatah Islam has claimed only 10 have been killed.
Nahr el-Bared's population is pegged at 31,000. About half of those have fled the town and are staying at the nearby Beddawi camp.
Country split
The nation's ties are deeply divided between those who support the pro-Western government and those who back the Hezbollah opposition -- which has the support of Iran and Syria, the U.S.'s two main foes in the Mideast.
As a result, the U.S. aid is likely to be a sensitive issue, coming amid opposition accusations that the government is too closely allied with the U.S.
Sheik Hassan Nasrallah, the leader of Hezbollah, said Friday that Lebanon is being dragged into a U.S. war against al Qaeda that would destabilize the country.
Nasrallah, along with Palestinian faction, called for a negotiated solution to the standoff, instead of a military one.
"Does it concern us that we start a conflict with al Qaeda in Lebanon and consequently attract members and fighters of al Qaeda from all over the world to Lebanon to conduct their battle with the Lebanese army and the rest of the Lebanese?" Nasrallah said in a televised address.
Defence Minister Elias Murr said he is leaving room for political negotiations, but said the military will do whatever is necessary, if talks fail.
Palestinian factions have been scrambling to find a negotiated solution to end the siege and avert what many fear would be a bloody battle between the Lebanese army and the Fatah Islam militant group in Nahr al-Bared.
"As long as we agree on the necessity of a solution and we speak with a language of solution then there is optimism," Hamas' representative in Lebanon, Osama Hamdan, said late Friday after meeting the head of the largest parliamentary bloc.
Defense Minister Elias Murr said Friday he was "leaving room for political negotiations," which he said must lead to the surrender of the fighters from the Fatah Islam militant group inside the camp.
"If the political negotiations fail, I leave it to the military command to do what is necessary," he told reporters.
Aid has also arrived from Arab nations. In the last few days, four planes have arrived from the U.S. Air Force, two from the United Arab Emirates and two from Jordan.
Lebanon has confirmed that it received supplies from the U.S. and Arab countries, but gave no details about what the aid included.
The U.S. will send eight transports, AP reports, all part of an aid convoy agreed upon earlier, but expedited at Lebanon's request.
Media reports have said the shipments contained ammunition, body armour, helmets and night-vision equipment -- all equipment that could be useful in a pitched, urban battle inside the camp, which is a densely built town comprised of narrow streets.
With files from The Associated Press
