A joint United Nations (UN) report said nearly 200 women and girls were raped by government troops and rebels in the eastern Democratic Republic of the Congo (DRC) last November, Xinhua news agency reported.

The UN Joint Human Rights Office (UNJHRO) in the DRC detailed in its report accounts by victims and witneses of mass rape, killings and arbitrary executions and violations resulting from widespread looting last year during fighting between government forces and M23 rebels in the DRC's restive eastern region.

UN spokesperson Martin Nesirky said that the UNJHRO -- made up of the UN Stabilisation Mission in the DRC (MONUSCO) and the office of the High Commissioner for Human Rights in the DRC -- reported systematic and violent abuse committed by the Congolese Armed Forces (FARDC) as they fled advancing M23 rebels in North Kivu province and regrouped in South Kivu.

"The UN investigation documented 135 cases of sexual violence perpetrated by FARDC individuals in and around Minova town as units retreated from the front lines. The victims included 33 girls aged between 6 and 17," said Nesirky.

"During the period of their occupation of Goma and Sake, M23 combatants perpetrated serious violations of international humanitarian law and gross human rights violations and were responsible for at least 59 sexual violence cases."

Elements of the 41st and 391st battalions of the FARDC were suspected of involvement in the violations, and a parallel investigation by the FARDC had led to the arrest of 11 soldiers in connection with the Minova incidents with two charged with rape.

Another 12 senior officers have been suspended while Congolese justice authorities are making investigation into the incidents.

UN High Commissioner for Human Rights Navi Pillay was quoted as saying that recent efforts by the DRC authorities to investigate the incidents in North and South Kivu were an important step towards accountability "but much more needed to be done."

The eastern DRC has witnessed armed clashes over the past months, after a newly-formed rebel group M23 launched an insurgency in North Kivu in early 2012.

The M23 rebels seized Goma, capital of the North Kivu province, before pulling out under regional pressure to facilitate peace talks late last year.