Kinshasa - Ugandan Lord's Resistance Army rebels killed more than 400 people in Christmas massacres in northeastern Democratic Republic of Congo, the Caritas aid charity said on Tuesday.
The rebels denied any responsibility and accused troops from DR Congo, Uganda and South Sudan of "bombing" the victims.
The LRA targeted a town where a Christmas Day concert was being held and a Roman Catholic church, and attacks were going on along the Sudanese border, the Catholic charity said in a statement.
Caritas workers say that "over 400 people have been killed in the attacks in an area of northern Congo including Faradje, Duru, Gurba, Doruma, and Province Orientale," it added.
The archbishop of Dungu-Doruma, Monsignor Richard Domba, said that at least 150 people had been killed at a Christmas Day service at Faradje and later, 80 at Duru and at least 200 others at Doruma and in the surrounding villages.
"It is a dramatic situation that we are living through here," he said.
"They kill with machetes, axes and clubs. They burn people alive with their property in their homes."
The LRA also "captured young boys and girls whom they will conscript and force to work in their fields," he said.
In Bangadi near the border with Sudan 48 people died and in Gurba 213 people were killed. Approximately 6 500 people have found refuge in the area with the Catholic church, Caritas said.
"The rebels have committed terrible acts of violence," said the director of Caritas in Dungu-Doruma, Abbe Come Mbolingaba.
"They decapitated several people. In the villages hardly anybody is moving.
"Everyone is in psychological shock. The death toll could be above 400 because it is difficult to find all the bodies."
Aid workers are worried by the lack of access in the region to local people who are wandering in search of shelter and help.
The Caritas statement said that the areas had been plundered, leaving the population in desperate need of aid. It said that the number of dead bodies risked spreading disease.
The United Nations mission in DR Congo (MONUC) said the LRA attacks followed the launching on December 14 of a joint military operation, conducted by DR Congo, Sudan and Uganda.
The operation followed the repeated refusal of LRA leader Joseph Kony, who is believed to be accompanied by several hundred supporters, to sign a peace deal with Kampala.
A spokesperson for the LRA said that it was not responsible for the massacres, blaming the deaths on bombs dropped by the three African forces and said it had never harmed anyone.
He questioned how the three countries would let LRA forces kill civilians.
In April the Ugandan authorities initialled a peace deal designed to end one of Africa's most savage and long lasting civil wars.
Tens of thousands of people have been killed and nearly two million displaced in Uganda in two decades of fighting between the Ugandan government and the LRA, which is notorious for abductions of children to be used as soldiers and sex slaves.
The Ugandan army said Sunday that rebels had massacred 45 civilians in a church on Friday, most of them women, children and the elderly.
The rebellion began in northern Uganda in 1986 after Yoweri Museveni came to power and blends a form of Christianity with traditional beliefs and extreme cruelty and brutality.