Later in the day Lebanese forces shot dead a member of Fatah al-Islam in Tripoli as the man tried to detonate a grenade during a raid on an apartment, the security forces said.
Shaheen al-Shami, the Fatah al-Islam commander who spoke to Al Jazeera said his men could take the battle outside the camp and accused the US of being behind the fighting.
"We understand that the army were dragged into this fight by a third party in the Lebanese government, this third party is working to implement an American plan," he said.
"The Lebanese army says they came to protect Lebanese soil and citizens but we see that certain parties within the Lebanese army are working to serve this American project."US military aid
The US, which provided $40m in military aid to Lebanon last year, has said it was considering providing extra assistance.
|Thousands of refugees have fled the|
camp since a truce was declared [AFP]
"The Siniora government is fighting against a very tough extremist foe," Condoleezza Rice, US secretary of state, said.
"But Lebanon is doing the right thing to try to protect its population, to assert its sovereignty and so we are very supportive of the Siniora government and what it is trying to do."
The Palestine Liberation Organisation has said it would not object if the army sent troops into the Nahr al-Bared to root out the fighters despite a forty-year-old agreement not to interfere in the refugee camps.
"This is a Lebanese decision, this is Lebanon's decision," Abbas Ziki, the PLO representative in Lebanon, said.
"We have declared that the country is for Lebanon and sovereignty is for Lebanon, and whatever Lebanon decides or considers its higher interests, we support it."
Elias Murr, the defence minister, urged the fighters still inside the besieged refugee camp to give themselves up.
"The army will not negotiate with Fatah al-Islam, which has two choices: either surrender or the army will take the military option," he said in an interview on Al-Arabiya television.
"The army has made its military preparations which I will not disclose."
A Lebanese defence ministry source told the Reuters news agency on Wednesday that at least 50 fighters from Fatah al-Islam have been killed since Sunday.
The body of the group's second-in-command was among those found near the camp on Wednesday, Lebanese military officials said.
The officials, speaking on condition of anonymity, said that Lebanese civil defence personnel retrieved the body of Abu Madyan in the area of Abde, just north of Nahr al-Bared.
The International Committee of the Red Cross has estimated that between 13,000 and 15,000 refugees have fled the Nahr al-Bared since the fighting halted on Tuesday.
Most of them have headed for the nearby Beddawi camp or the homes of relatives in Tripoli or surrounding towns.
Sultan Abul Aynayn, the head of the mainstream Fatah movement in Lebanon, issued an urgent appeal for humanitarian organisations to help, saying the displaced refugees were "totally destitute."
Hoda Samra, spokeswoman for UN Palestinian refugee agency, said: "We are providing relief aid to the thousands of refugees who have sought refuge in our schools and centres in Beddawi and Tripoli."
"Our clinics are also working double shifts in order to cope with the number of refugees and provide them proper services."