More than 20,000 people, mainly Sudanese refugees, have fled their homes in northeastern Uganda in the past three weeks after an upsurge of attacks by rebels, a UN official said Sunday.

"Some local villagers as well as Sudanese refugees have fled their settlements in Adjumani (600 kilometres / 370 miles northwest of Kampala) and were migrating to safer areas mainly by crossing over River Nile into Moyo district while some settle on the fringes of the river," Dennis Duncan, spokesman for the UN refugee agency told AFP in Kampala.

He said the rebel Lord's Resistance Army (LRA) has been carrying out raids on refugee camps in the area to steal food and medical supplies.

"Though they have not killed anybody, both the locals and refugees alike know what the LRA is so about 20 000 of them are migrating west carrying along with them their household possessions," Duncan added.

He said that refugee settlements affected include Maji, Mungula and Olua in Adjumani district.

Duncan said that investigators from the UN High Commissioner for Refugees (UNHCR) and the Ugandan government had gone to Adjumani and the neighbouring Moyo district to assess the situation.

He said the army has deployed a battalion of soldiers in the area to beef up security.

Duncan said that LRA fighters had attacked refugee settlements nine times this month and disrupted UNHCR activities in the area, forcing the agency to close down schools and withdraw some of its equipment for fear of looting.

"The self-reliance programme we started with the refugees has been interrupted meaning that we shall have to wholly feed these refugees as they have not been able to utilise the current planting season," he explained.

The Lord's Resistance Army (LRA), at war with the Ugandan government for nearly two decades, is notorious for committing atrocities against civilians, including forcing children to serve as soldiers or sex workers - Sapa-AFP.