Lebanese army — backed by a missile firing helicopter — stepped up the offensive against Al Qaeda-inspired militants Saturday, on the second day of a push against Islamic fighters who have vowed to fight to death inside a Palestinian refugee camp.

Army tanks shelled militant hideouts in the Nahr el-Bared camp by this northern port city, blasting upper floors of buildings where the militants had placed snipers. Plumes of smoke rose sky high.

For the first time since the military's confrontation with the Fatah Islam group began May 20, a Lebanese airforce helicopter fired two missiles and strafed militant positions.

Four more soldiers were killed and 10 wounded Saturday, bringing the army's casualties to six dead and 20 wounded since the Friday's start of the offensive.

The casualties raised the army's deaths to 38 in the last two weeks. At least 20 civilians and about 60 militants had also been killed by Friday, but casualties in the camp in the last two days were unknown, as relief organizations were banned from entering.

The push by hundreds of elite Lebanese troops and tanks underscored the pro-Western government's determination to wipe out the fighters barricaded inside the camp's residential neighborhoods.

Prime Minister Fuad Saniora said there were still about 250 members of Fatah Islam — which he said was "involved with intelligence agencies in Syria" — inside the camp. Saniora promised Palestinians who fled Nahr el-Bared that they will be able to return and that the "camp will be rebuilt."

The militants "have no choice but to surrender," Saniora told Dubai-based Al-Arabiya television, adding that the government would "assure this group justice and a fair trial."

There were also signs that Palestinians trapped inside the camp were trying to squeeze the militants out.

Abu Jaber, an official of the Popular Front for the Liberation of Palestine — a key Palestinian guerrilla faction that has stayed out of the fighting — told Lebanese Broadcasting Corp. television that Palestinians were trying to "isolate" the militants by locking up houses and barricading camp neighborhoods to keep them out.

Many Palestinian refugees have backed the army, saying they want the military to finish off Fatah Islam, considered by some a radical Sunni Muslim group tied to Al Qaeda or inspired by Al Qaeda's militancy and doctrine. Others, like Saniora, believe it linked with Syrian military intelligence aimed at destabilizing Lebanon — a claim Syria denies.

Abu Jaber said that 17 people had been wounded in the camp and some 400 houses destroyed in the shelling Saturday. "We hope that the army realizes that the shells are falling on the heads of innocent people," Jaber said by cellular phone from Nahr el-Bared.

Conditions on the ground were unclear. Journalists were pushed back from the camp and aid organizations were not allowed inside. Most of the camp's 31,000 refugees fled to the nearby Beddawi camp earlier in the fighting, but at least 5,000 are believed still inside.

Contrary to official claims that dozens of Fatah Islam had been killed and wounded since Friday, the group's deputy commander Abu Hureira said only two fighters had been wounded in the last two days.

Abu Hureira conceded that his fighters abandoned some positions on the camp's northern edge in a "tactical" withdrawal, denied the army had advanced and vowed never to surrender.

"Let them come. We are ready," Abu Hureira told The Associated Press by cellular phone, gunfire crackling in the background as he spoke. He also denied reports that he and the group's leader, Shaker Youssef al-Absi, were wounded.

The army's French-made Gazelle helicopter fired two missiles and machine gun fire at suspected militant hideouts on Nahr el-Bared's western edge toward the Mediterranean coast — in an apparent attempt to block a sea escape route.

An army officer, speaking on condition of anonymity because he was not allowed to talk to the media, said the troops will "continue advancing today and hopefully, we will end it."

Lebanese security officials, also speaking on condition of anonymity because they were not authorized to make statements to media, said Nahr el-Bared had been strategically divided into three zones. The army was controlling one zone, the militants held another, while Palestinian civilians and guerrillas controlled the third and were refusing the militants sanctuary, they said.

The army said the militants had taken up positions in the camp mosques and humanitarian centers, storing weapons inside and holding civilians as "human shields." It was not clear how the military knew this or how many Palestinians were used as human shields.

Standing on the balcony of her building overlooking the camp, a 43-year-old Lebanese woman who identified herself only as Um Omar, said the people were tired of the fighting.

"We don't care who's right or who's wrong, who are the good guys and who are the bad guys. We just want this to be over," she said.