Thousands of Palestinians streamed out of a refugee camp in Lebanon overnight Tuesday and early Wednesday during a break in fighting between government troops and Islamic militants.

About 15,000 civilians fled the Nahr el Bared camp in northern Lebanon late Tuesday to seek shelter at the Beddawi refugee camp, about 10 kilometres to the south. Another 1,000 left early Wednesday.

Reception centres and a functioning hospital are available at Beddawi.

The refugees, including pregnant women getting ready to give birth, streamed out of the camp when a truce took hold after sundown. The exodus followed days of hunkering down to avoid fighting between Lebanese troops and Islamic militants dug in at the heart of the camp.

Ruba Khoury, co-ordinator of World Vision's aid program in Lebanon, told CBC News on Wednesday that relief agencies had made contact with the people who have left the camp. She said many are in need of food, shelter and medicine.

"It's a rapidly evolving situation," she said by telephone from Beirut. "Yesterday, we couldn't get through to the refugees. Today, we have at least 12,000 who have been moving throughout the night outside the camp.

"Unfortunately, they are the most vulnerable. They are the women, the children, the disabled. They have basic needs that need to be met."

Worst fighting since civil war

Fighting between the Lebanese army and Fatah al-Islam, a militant group believed to have links to al-Qaeda, erupted Sunday in Lebanon's worst internal violence since the 1975-1990 civil war.

The militants took up residence late last year in the camp, which the troops are not allowed to enter under a deal between Lebanon's government and Palestinian officials.

Since the fighting began on Sunday, however, refugees have been caught in small arms fire and shelling from both sides.

Khoury said non-government groups need to put together a plan to help the refugees streaming out of the camp, which originally contained 31,000 people, mostly Palestinians. A UN aid convoy sent in to help residents was shelled. 

'It would be like a nightmare inside the Nahr el Bared camp.'—Ruba Khoury

Officials said the bodies of at least 20 civilians have been retrieved from the camp. Inside, it is said to be a scene of devastation. Homes have been destroyed, cars have been burned and bodies are strewn in streets.

Khoury said the camp was in poor condition before the fighting began, but now, there is no electricity and no water.

"You can hear children screaming. I guess it would be like a nightmare inside the Nahr el Bared camp," she said.

Dr. Ahmed al Haj, who works at the hospital in the Beddawi camp, said he has seen 21 pregnant women. Some went into premature labour, and some lost their babies.

He said there is no hospital in the Nahr al Bared camp.

"They haven't surgical instruments or anesthetic," he said.

A reception centre has been set up in one of the UN schools in the Beddawi camp and the courtyard is full of people trying to locate friends and neighbours.

Munir Asayed, an English teacher, said the Lebanese government simply abandoned the Palestinian civilians inside the Nahr el Bared camp to their fate. Many of the refugees are very angry.

"I blame everybody in the world. We have no relations with Fatah el Islam. They were firing from outside the camp. But what about us? We who were inside the camp?" Asayed said.

The Lebanese government has said it is determined to uproot the militants, and on Wednesday, the Lebanese army reinforced its positions around the camp.

Arbour calls shelling of convoy unacceptable

Lebanon has 12 Palestinian camps that contain about 400,000 refugees, according to Reuters news agency.

"They're a breeding ground for any type of mishap," security analyst Timur Goksel was quoted as saying by Reuters. "You are in a sovereign country and you have these autonomous enclaves."

Louise Arbour, UN High Commissioner for Human Rights, said in a statement on Wednesday that the shelling of a UN convoy is unacceptable.

The convoy was trying to deliver emergency supplies, including milk, bread and medicines. Three vehicles in the convoy were badly damaged and some of the supplies destroyed.

Arbour said all parties to the fighting in Nahr el-Bared have an obligation to exercise caution and to protect civilians not taking part in the hostilities.

"The protection from attack for humanitarian workers and medical personnel and their unrestricted access to civilians are also guaranteed under the principles of international humanitarian law," she said.

Some residents of the camp have fled to a stadium in the nearby city of Tripoli, where the UN Relief and Works Agency for Palestine Refugees in the Near East is organizing relief efforts.

With files from the Associated Press