BEIRUT, Lebanon (CNN) -- The Lebanese army pounded a Palestinian refugee camp in northern Lebanon with heavy artillery Thursday in what one high-ranking Lebanese security source described as a final bid to oust the Islamist militants entrenched inside.
People flee the embattled Palestinian refugee camp near the southern entrance blocked by Lebanese army trucks.
The Lebanese army, however, denied the shelling constituted a final push, describing the operation as continued pressure on the militants.
Fighting around the coastal Nahr al-Bared camp has been simmering on and off for about eight weeks, but flared Thursday as fresh army reinforcements were brought into the area as part of a final assault, the source said.
The sounds of artillery could be heard as black smoke billowed over the bombed-out refugee camp, some from fires triggered by the shelling.
The Lebanese army said they had killed a number of militants in the renewed clashes, but were unsure how many remained holed up inside. Watch how Lebanon launched assault »
Since the beginning of the assault against the Fatah al-Islam fighters -- which are said to have ties with al Qaeda -- scores of militants and at least 88 Lebanese service members have been killed.
The army said another soldier was killed on Tuesday by sniper fire coming from within the camp -- a tactic that has become a danger for troops in the area. A number of soldiers have been killed by snipers before, the army said.
The sometimes-fierce battles mark the worst internal violence since the end of Lebanon's civil war in 1990.
The violence began May 20, when Lebanese internal security forces were conducting raids in a Tripoli neighborhood, triggering clashes near the refugee camp. Army sources said militants from Fatah al-Islam fired on the forces, who then returned fire.
The fighting in the north is an added concern for Lebanese Prime Minister Fouad Siniora one year since Hezbollah guerrillas in the south of the country crossed the Israeli border, killing three soldiers and capturing two, who have yet to be released -- prompting Israel to unleash a massive bombing campaign and invasion of Lebanese territory.
Attempts at mediations between Islamist leaders and the militant group have failed, and the military's top commanders have insisted they will crush the militants if they do not surrender.
Previous military operations launched against the camp have included a barrage of 155mm artillery rounds and a naval gunship.
The Lebanese army has launched attacks from nearby the camp, but troops have not ventured inside the camp's parameters, as part of a 1969 agreement that allows the Palestinian refugees to run the camps.
Meanwhile, most of the roughly 30,000 Palestinians who used to live in the once-overcrowded camp have now fled. Some left on foot carrying babies and only a few belongings, while others crammed into cars and vans. E-mail to a friend