The International Committee of the Red Cross (ICRC) says at least 800 people have been killed during the capture of a major city in the western Ivory Coast, Press TV reported.
"At least 800 people were killed in Duekoue on Tuesday," ICRC spokeswoman Dorothea Krimitsas said on Friday.
Red Cross representatives had "themselves seen a very large number of bodies," she was quoted as saying by AFP.
"There is no doubt that something on a large scale took place in this city, on which the ICRC is continuing to gather information," she added.
The day saw forces backing president-elect Alassane Ouattara claiming to have seized the city during an all-out battle with troops loyal to incumbent President Laurent Gbagbo.
The West African nation has been in crisis since Gbagbo refused to acknowledge losing November's presidential election to Ouattara.
Post-election violence has left at least 494 people dead. A United Nations report has also said that up to one million people have fled their homes so far.
Earlier the UN Human Rights Office warned Ouattara against committing human rights violations.
Reports say pro-Ouattara forces have abducted and mistreated civilians. There are also reports that loyalists to Gbagbo are responsible for bloodshed of civilians.