Six Chadian peacekeepers were killed on Christmas Day in Central African Republic amid sectarian fighting that has engulfed one of the world's poorest countries.
The soldiers are believed to have been killed by Christian anti-balaka, who see the Muslim Chadian peacekeepers as taking sides in the conflict.
Two days of intense fighting between Christian and Muslim militias have left scores dead.
The African Union said on Thursday that it had found a new mass grave filled with 20 bodies in the capital Bangui near the presidential palace.
"We found around 20 bodies in a state of decomposition in an area that we call Panthers' Hill. The 20 were scattered in different graves in a small area," said African Union spokesman Eloi Yao.
"The bodies were wearing civilian dress, but we cannot know if they really were civilians or if they were militiamen," he added.
The International Red Cross said that it had recovered more than 40 bodies from the streets of Bangui over the past two days,
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The group said that many of the victims seemed to be civilians.
The Associated Press wrote that atrocities have been mounting on both sides, with executions and mutilations, and bodies being left to rot on the streets.
About 1,600 French soldiers have been deployed to the former colony to keep the peace, along with thousands of other soldiers from the African Union.
Both the African and French peacekeepers have been accused of taking sides in the conflict with Christians attacking Muslim peacekeepers and Muslims attacking French soldiers.
Both have worked to try and disarm militias and halt the violence that has gripped the country since tensions began to arise after a coup in March.
It is estimated that 639,000 people out of the country's 4.5 million people are displaced. About two million people are in need of humanitarian aid.
Bangui's main hospital received more than 50 people with gunshot or machete wounds since Wednesday night, according to the Guardian.
President Michel Djotodia appealed for calm this week, urging citizens of the country to "love each other."
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