The United Nations mission in the Democratic Republic of Congo, Monuc, has demanded the punishment of 78 soldiers accused of raping 119 women.
Many women in the DRC have become victims of rape
The soldiers are accused of the gang rape in north-eastern Equateur province following a mutiny on 21 December 2003.
Minuc said it had given the authorities the names of the suspects in April but they had yet to be interrogated.
The UN is itself investigating some 150 allegations of sexual abuse by UN civilian staff and soldiers in the DRC.
Accusations against the UN include paedophilia, rape and prostitution at a UN site in Bunia.
Soldiers from the 9th Battalion of the DRC army mutinied in December after accusing their commanding officer of stealing their pay.
They were then allegedly involved in gang-raping women and girls in Nsongo Mboyo, as well as looting afterwards.
Monuc said it accompanied a team from the Congolese human rights ministry and military investigators to Mbandaka, the main city in Equateur province, in May, where "more than 200 complaints were filed with them by victims of rape or looting".
"Monuc is worried that one year after the crimes and in spite of the significant efforts made by the human rights ministry, no initiative has been taken by the military to question the suspects," the mission said in a statement.
"The impunity of those responsible for this mass rape is a cause of deep concern," the statement said.
"Not only because of the gravity of the crime, but also because it is important that the transitional government gives an unequivocal signal to troops in its newly integrated army that such abuses will be punished," said the UN mission.