According to researchers report in this months American Journal of Public Health more than 400,000 women aged 15 to 49 were raped in a 12 month period.
"Previously, Congo's sexual violence has been framed as women and children caught between two armed groups in eastern Congo," said Lisa Shannon, founder of A Thousand Sisters, a human rights campaign group in the US.
"But these numbers show us that conflict in the east has produced a rape pandemic of astronomical proportions, but that the pandemic is not contained. We now know high levels of sexual violence exist even in non-conflict areas."
Earlier studies, including one by the United Nations last year, suggested that 15,000 women were raped during the research period in 2006 and 2007.
