Lebanon's army on Saturday pounded al-Qaida-inspired Islamic militants hiding in a Palestinian refugee camp in renewed heavy clashes following a few days of intermittent fighting. Black smoke billowed from the Nahr el-Bared camp in northern Lebanon where witnesses reported some of the heaviest army shelling since June 1, as the Lebanese army, using tanks and artillery, launched an offensive to drive the Fatah Islam militants from their positions inside the settlement. Ambulances were seen rushing to the area of the camp, and security officials said three soldiers were killed and around 17 were wounded in the fighting Saturday morning, some of them seriously. The officials spoke on condition of anonymity because they were not allowed to give official statements. The army sent heavy reinforcements, including armored carriers and special combat units, which were spotted heading toward the camp. The main road linking Tripoli with the province of Akkar and the Syrian border was closed Saturday for the first time in several days. It was not immediately clear if the army intended to make a final push toward the camp in its attempt to uproot the militants hiding there. Local and Arab television stations billed it as a major army assault on militants inside the camp, but a senior Fatah Islam commander denied the reports and said fighters were holding their ground. "We are steadfast and, God willing, we will not retreat for one moment. Let them (army) advance if they want. ... We are on the front lines across from them," Abu Hureira, Fatah Islam's deputy commander, told The Associated Press by telephone from inside the camp. Abu Hureira, whose real name is Shehab al-Qaddour, dismissed as "rumors" media reports that he and Fatah Islam leader Shaker Youssef al-Absi were wounded. He said some fighters were "lightly" injured "but it's nothing compared to them," he said, referring to Lebanese army casualties. He said the militants were still fighting with the same tenacity, claiming that Fatah Islam fighters attacked an army position on the northern edge of the camp Friday and seizing weapons from Lebanese army soldiers. In a statement issued Friday, the army said it was "gradually taking control of the terrorists' positions" in Nahr el-Bared to end this "abnormal phenomenon ... imposed on Lebanon." The statement did not say how many militant positions were overtaken so far. More than 120 people, including at least 60 Fatah Islam militants, 46 soldiers and 20 civilians, have been reported killed in the fighting, the worst internal violence in Lebanon since the 1975-90 civil war. Recent civilian casualties are not known because the camp has been closed to journalists and aid workers for days. Though most of Nahr el-Bared's residents have fled, thousands remain trapped inside. A United Nations spokeswoman denied media reports Saturday that the UN peacekeeping mission in south Lebanon, known as UNIFIL, had raised its alert level because of unconfirmed reports that interrogations with captured militants had revealed plots to attack the expanded UNIFIL force that was formed after last summer's war between Israel and Hizbullah. "There is absolutely no raised threat. We have full confidence in the Lebanese armed forces to secure law and order throughout the country," said UNIFIL deputy spokeswoman Yasmina Bouziane.