Nepal was gripped by a communist insurgency that left more than 13,000 people dead before a peace process was started in 2006. Both the Maoist rebels and government forces were accused of widespread rights abuses during that time.

Richard Bennett, who heads the U.N.'s human rights office in Nepal, said about 1,300 people's whereabouts are still unknown, and most of their cases have yet to be investigated despite his agency's repeatedly asking the government and former rebels to help.

"No one has been brought to justice in conflict-related cases," Bennett said Wednesday.

He said some of those responsible for the disappearances even hold high positions in the Communist Party of Nepal (Maoist), the political party the rebels formed when they gave up their weapons.

He said he wanted to see proper independent investigations into all those who disappeared.

Maoist and government officials could not immediately be reached for comment.

Both the army and the rebels are thought to be responsible for disappearances during the fighting. Soldiers were given the power to arrest suspects without warrant and question them, and many are believed to have died in custody. The rebels, meanwhile, are accused of executing those they thought were helping the government.