(Adds civilians evacuated, details)

By Nazih Siddiq

NAHR AL-BARED, Lebanon, Aug 24 (Reuters) - The Lebanese army has evacuated families of Islamist militants who have been fighting troops at a Palestinian refugee camp, a military source said on Friday.

The militants and their families have been holed up at the Nahr al-Bared camp since the conflict began on May 20. The fighting has killed nearly 300 people, the worst internal violence since Lebanon's civil war ended 17 years ago.

"We have received 63 civilians -- 25 women and 38 children," the source said.

Witnesses said they saw a military bus filled with women veiled completely in black leaving the camp, flanked by a convoy of army vehicles and with ambulances following behind.

Security sources said the civilians were taken to a nearby military base for questioning. Two children were taken to hospital.

The camp has been almost totally destroyed by intense tank, artillery and helicopter fire from the army, which is trying to force the al Qaeda-inspired Fatah al-Islam group to surrender.

Lebanese security sources said there were no more than 30 active fighters left in the camp, suggesting the evacuation could be a precursor to a surrender by the group.

The militants had asked Palestinian mediators earlier this week to secure a truce to allow their families to leave.

Most of the camp's 40,000 residents fled to a nearby Palestinian refugee camp in the first days of fighting.

Fatah al-Islam split from a Syrian-backed Palestinian faction last year. It says it shares al Qaeda's ideology but has no organisational ties to Osama bin Laden's network. (Additional reporting by Laila Bassam)

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