Aid groups have called for efforts to prevent mass killings by one of Africa's most feared rebel militias over the Christmas period.
The aid agencies say a concerted effort is needed to stop the Lord's Resistance Army (LRA) from committing what have become known as "Christmas massacres".
LRA fighters killed hundreds of people in the Democratic Republic of Congo and Sudan in December 2008 and 2009.
Hundreds of people were abducted during those attacks.
Figures show that the LRA over the past two years has become the most deadly militia in the DRC, the aid groups say in a report.
On Christmas Day 2008 and over the following three weeks, LRA beat to death more than 800 people in north-eastern DR Congo and Southern Sudan, abducting hundreds more.
In December 2009, the brutal militia killed more than 300 villagers in DR Congo in the run-up to Christmas.
An LRA spokesman denied that his organisation was responsible for the atrocities.
The rebels - originally from Uganda and also roaming across parts of Sudan and the Central African Republic (CAR) - killed or abducted more than 1,000 people in remote areas of DR Congo last year alone, the report says.
"The LRA abducts, mutilates, rapes and kills women, men and children, using extreme violence against the most vulnerable," the report adds.
The militia is also notorious for kidnapping children to save as soldiers and sex slaves.
"It is unbelievable that world leaders continue to tolerate brutal violence against some of the most isolated villages in central Africa and that this has been allowed to continue for more than 20 years," said Marcel Stoessel from Oxfam, one of the 19 organisations behind the report.
US President Barack Obama in November outlined a plan to remove the LRA's leader, Joseph Kony, and disarm the LRA. Mr Kony is wanted by the International Criminal Court (ICC).
Mr Obama was responding to US legislation passed in May promising a comprehensive strategy to put a stop to the LRA's killings, rapes and mutliations.
But the new report says more humanitarian aid and a more concerted military effort is needed to stop the rebels from committing more atrocities.
"Recent signs of diplomatic commitment from the African Union and the United States must provide tangible answers that protect the population from violence," the agencies say.
The report also calls on the UN Security Council to put the rebel group on its agenda.