Local sources have said that the victims were killed by rebels in a village called Makobola about 15 kilometres south of the town of Uvira in the east of the country.

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Rwandan soldiers, who support the rebels, are reported also to have taken part.

The sources said the killings appeared to be a reprisal for a previous attack by a group of Congolese nationalist partisans called the Mai Mai in which several Tutsi soldiers had been killed.

However, rebels in the area denied any killings had taken place. A local commander, Jonas Padiri, said the area was quiet and there had been no problems.

'Work of the Devil'

The Catholic Misna news agency based in Rome, which reports for all 40 Catholic missionary orders working in Africa, said that the commander of the soldiers who carried out the massacre was a Rwandan known locally as Shetani, meaning the Devil.

It said entire families who belonged to local ethnic groups and different Christian denominations had been slaughtered by machete or gun.

Father Giulio Albanese, the director of the agency, told the BBC that the massacre took place during three consecutive days between 30 December and 1 January.

He said: "We are receiving little by little the names. Counting has not ended. There are roughly 500 dead. It's something unbelievable."

Fear and tension

He said there was still great tension in the area and the civil population was living in great fear.

Around 350 people were killed in a similar reprisal attack in the same area last August.

The reason why news of the killings has just emerged is because the sources who were in touch with Rome wanted to count the dead and bury them first in order to give as full an account as possible to the outside world.

Fighting continues

The conflict in DR Congo has forced thousands to flee

Congolese rebels launched an offensive in the east last August in an effort to topple President Kabila.

They have tried to win the support of the Mai Mai traditional warriors, but have largely failed.

The rebels now control much of the eastern half of Congo, but they are divided by power struggles and differences over how to restructure the movement.

The rebels have military support from neighbouring Rwanda and Uganda, while Mr Kabila's army is bolstered by troops from Angola, Zimbabwe, Chad and Namibia.

Thousands of people have fled violence in the region since the rebel offensive began and fighting between the Mai Mai and Tutsis has been frequent.