ABIDJAN (Reuters) - Militiamen loyal to former Ivory Coast president Laurent Gbagbo killed 120 people during a "scorched earth" retreat from Abidjan last week, the Defence Ministry said.
The United Nations said it was investigating the report.
The once-prosperous West African nation is counting the cost of a violent five-month power struggle between Gbagbo and President Alassane Ouattara that killed at least 3,000 people and uprooted over a million.
Gbagbo, who refused to quit despite U.N.-certified results showing he lost November's election, was arrested on April 11. But fighting continued in parts of Abidjan until militiamen and Liberian mercenaries loyal to him were routed last week.
"Chased by the Republican Forces, they practiced a scorched earth tactic as they fled, destroying everything in their path," a ministry statement said.
Ouattara was sworn in as president last week, but he now faces the momentous task of reuniting a country bitterly divided by conflicts over land, nationality and revenge killings.
The statement accused militiamen and Liberian guns-for-hire loyal to Gbagbo of killing civilians in the coastal towns of Irobo, Grand Lahou, Gonfroto and Niegreboue on May 5-6.
In total, it listed 120 people killed, of which all were civilians apart from two soldiers. In addition, it said Ivorian forces had killed 30 militiamen in one gun battle.
"We are conducting our own investigation. We are sending our team to those areas. At this point in the investigation, we cannot confirm the allegations," U.N. human rights officer Guillaume Ngefa told Reuters by telephone.
Ouattara is seeking to try Gbagbo for alleged war crimes, but he also promises a South Africa style truth and reconciliation commission to enable Ivory Coast to move on after some of the worst violence in its history.
A U.N. investigation this week confirmed the killings of 68 Ivorians by pro-Gbagbo forces in the Abidjan district of Yopougon the day after Gbagbo was seized. Their bodies were buried in a football pitch by relatives
Ngefa said four U.N. teams were investigating reports of abuses by both Ouattara's and Gbagbo's forces -- in the west, centre, the southern coastal region and in Abidjan.
The results would be published in the coming days or weeks.
"A lot is not yet clear. There are rumours and a lot of manipulation, so you have to be careful," he said.