Ugandan rebels have freed five aid workers taken hostage at a United Nations-run camp six days ago, aid officials said.

Timothy Bishop, from the International Rescue Committee (IRC) in Uganda, said the men were released overnight near the town of Lira.

They have bruises all over their bodies from walking through the bush

Timothy Bishop, IRC

"Yesterday evening, all of the five IRC workers abducted in Monday's attack at Acholi-Pii were released," said Mr Bishop.

"They have bruises all over their bodies from walking through the bush, but they are otherwise in good spirits," he said.

The men have been reunited with their families.

Dozens killed

The group were seized by members of the Lord's Resistance Army (LRA) who raided the camp in northern Uganda.

The LRA guerillas overpowered troops guarding the site, killing 38 people.

About 34,000 refugees fled from the camp during the attack.

The LRA has been fighting the government for 16 years and says it is seeking to rule Uganda according to the Biblical Ten Commandments.

The LRA says it attacked the camp to avenge the killings of LRA supporters in Sudan.

UN accused

In a statement issued on Thursday, LRA claimed the Ugandan army carried out the attack in collaboration with the Sudanese Government and rebels of the Sudan People's Liberation Army (SPLA).

The LRA says the Ugandan army has killed its members in Sudan

It said IRC workers at the Acholi-pii camp had been taken away because the United Nations had not protested at the death of civilian refugees killed by the Ugandan army in Sudan.

The attack came only three days after the Ugandan President, Yoweri Museveni, moved to the north of the country to take charge of operations against the rebels.

It was later followed by another rebel attack on Tuesday in which at least 15 rebels were killed in clashes with two army units in northern Uganda.

The camp at Acholi-Pii is now safe, according to the army, but the United Nations refugee agency has been moving the refugees to the central area of Masindi, which it believes to be more secure.