Bangui - Ex-rebel fighters loyal to the new leader of Central African Republic went on a rampage after toppling the former president, executing opponents, raping women and looting homes - acts that could constitute war crimes, Human Rights Watch (HRW) said.
Thousands of fighters from the Seleka rebel coalition led by Michel Djotodia marched into the capital Bangui on 24 March, forcing President Francois Bozize to flee to neighbouring Cameroon.
Djotodia, a former civil servant turned rebel leader, was later named interim president by the parliament and charged with leading the mineral-rich but chronically unstable nation to elections within 18 months.
While organisations including the United Nations and the International Criminal Court (ICC) have voiced concern at Djotodia's failure to end abuses, the HRW investigation is the first to document the full extent of the violence.
"If the Seleka coalition, as it claims, wants to undo the wrongs of the previous government, it should immediately end its horrific abuses," the rights campaigner's Africa director Daniel Bekele said in a statement released on Friday.
Central African Republic's communications minister said anyone responsible for abuses would be prosecuted, but added that many crimes being blamed on Seleka fighters had been committed by others.
"Many people have been arrested and are waiting to be charged," Christophe Gazam-Betty told Reuters. "But many are ex-members of the former presidential guard dressed as Seleka".
HRW researchers found evidence of scores of killings by Seleka fighters after the fall of Bangui, and received reports of other civilian deaths at the hands of the rebels elsewhere in the country both before and after they seized power.
Some of the deaths in the capital were the result of indiscriminate shooting, particularly in the Boy-Rabe and Ouango neighbourhoods, the statement said.
Others were killed when they resisted Seleka fighters attempting to loot their homes.
"My wife approached the door. But they kicked it down and shot her," one witness told HRW.
"[Our] baby was in her arms and she was hit in the head. My wife was then hit in the head and in the chest."
The woman and baby were killed instantly, the witness said.
Seleka fighters also rounded up men suspected of belonging to Bozize's army, many of whom were later executed.
Pillage, rape and murder all constitute war crimes under the statute of the International Criminal Court, HRW said, urging the body to closely monitor the situation in the country.
ICC prosecutor Fatou Bensouda said last month that she was concerned by the security situation in Central African Republic and would not hesitate to pursue those found to have committed crimes which fall under the jurisdiction of The Hague court.
Seleka, a grouping of five rebel movements, launched its insurgency in early December, accusing former president Bozize of reneging on a 2007 peace deal. (Additional reporting and writing by Joe Bavier; Editing by Michael Roddy)