By Will Ross BBC, Kampala

Rebels of the Lord's Resistance Army have attacked a camp for displaced people in northern Uganda and killed 13 civilians.

The army has been unable to end the LRA rebellion

President Yoweri Museveni promised earlier this year that the rebels would be defeated by the end of the dry season.

That was not achieved and now following considerable rainfall, the rebels have been taking advantage of the long grass attacking the civilians both in the villages and in the camps.

The Ugandan army has been unable to prevent the attacks and the civilians are calling for international intervention.

According to local officials the civilians were killed on Wednesday night when a group of LRA rebels entered Pabbo Camp which is 35 km north of Gulu town.

Those killed were from Pawal village and Pabbo camp.

Twelve were clubbed to death a few hundred metres from the camp, while a 13th was caught in crossfire between the rebels and the Ugandan army.

Suffering

According to local official Odoch Athii P'Obol Jok, as the deceased were being buried this morning, people in Pabbo were pleading for the international community to take action to end the war.

The official said the rebels left a letter, addressed to the people in the camp.

The letter says the killings were carried out because local officials and the military have in the eyes of the rebels incited the population to fight against them.

The letter which was signed by a Lieutenant Okwera is similar to a letter sent last week threatening to mutilate those choosing to fight on the government side.

Lieutenant Paddy Ankunda of the army's 4th division confirmed last night's attack had taken place.

He told me that in a different incident last night government troops killed nine LRA rebels at Zambia-Achokara on the border of Gulu and Apac districts.

Also last night the LRA attacked Opit trading centre and displacement camp some 20 km south-east of Gulu town.

The rebels burnt 30 huts and looted and abducted an unknown number of civilians.

While the army may be killing some rebels, frequent abductions of civilians means the rebels are constantly bolstering their force and civilians will continue to be the victims.

Meanwhile in his state of the nation address, President Museveni said on Thursday that in addition to pacifying Karamoja region, wiping out the LRA's Joseph Kony is his main priority.