One soldier was killed outright and three more were seriously wounded, two of them fatally, he said on the 35th day of the siege north of Tripoli.

"A fourth soldier badly wounded by the explosion is in critical condition."

He corrected an earlier report that the first soldier had been targeted by a sniper, and added that he was unaware of reports that an Islamist suicide bomber had attacked an army patrol.

The body of one militant had been retrieved from Nahr al-Bared, he added.

Yesterday's fatalities raised to at least 147 the number of people killed since May 20 in the deadliest internal violence since the 1975-1990 civil war.

The dead include 79 soldiers -- more than twice the number of Lebanese troops killed during last summer's 34-day Israeli onslaught against the Shiite Hezbollah movement.

Fatah al-Islam casualties are unknown, but at least 51 militants are believed to have been killed.

In a statement sent to AFP yesterday the army warned against "elements of the terrorist network."

"They must not be permitted refuge among the civilians in the camp, allowing them to continue their aggression against our soldiers," it said, adding that it would "respond energetically to sources of fire."

The military urged "the camp's population to take a courageous stand so it does not fall victim to these criminals who have only one choice -- to surrender and be brought to justice."

The latest clashes came a day after an Arab League delegation admitted failure in its latest bid to reconcile Lebanon's deeply divided Western-backed and pro-Syrian political camps.

Artillery pounded the Islamists as the army sought to end a siege that has lasted nearly five weeks. Extremists entrenched inside the warren-like camp responded with automatic fire, an AFP correspondent said.

The brutal standoff continued despite Defence Minister Elias Murr saying on Thursday that the onslaught against Sunni Muslim fighters of the Al-Qaeda-inspired Fatah al-Islam group "has ended."

Fires burned inside Nahr al-Bared and a pall of smoke hung over the southern part of the camp's single-storey buildings and narrow streets into which the remaining militants have withdrawn.

Their original stronghold in the "new camp" -- a high-rise spillover to the north from the original refugee camp whose boundaries were set by the United Nations in 1948 -- is now a wasteland of shattered concrete.

Some 2,000 residents of the camp's pre-battle population of 31,000 are still inside Nahr Al-Bared, with those who fled now dispersed among other Palestinian camps around the country, mostly at nearby Beddawi.

Sheikh Mustafa Dawood, who leads Palestinian clerics trying to broker a ceasefire, entered the camp on Friday and met militant spokesman Shahin Shahin who expressed a desire to honour a unilateral truce "in the hope of reaching a happy outcome."

But Dawood told AFP that Shahin also said "if there is shooting at us we will be forced to respond."

On the political front, an Arab League delegation has left Lebanon admitting it failed to bring Lebanon's pro- and anti-Syrian camps to the negotiating table to seek an end to a festering seven-month political crisis.

"Some ideas and theses proposed today hindered the possibility of reaching an official understanding" between the anti-Syrian parliamentary majority and the pro-Syrian opposition, league chief Amr Mussa told reporters.

He was ready to resume mediation "if things progress," he said.