Jan 24, 2007
Speaking after a six-day visit to the country, Louise Arbour told the BBC war crimes had been committed in Nepal.
At least 13,000 people were killed and hundreds went missing in the conflict.
The Maoists agreed to peace last year and are set to join a multi-party government. The parties and the Maoists say they will form a truth commission.
The BBC's Charles Haviland in Kathmandu says Ms Arbour's message is that severe human rights violations in Nepal in the past and present are made more likely by impunity, or what she called very poor law enforcement.
In her BBC interview, the UN high commissioner for human rights accused the country's political players of acting insultingly to victims of rights abuses committed during nearly 11 years of conflict.
She welcomed moves to set up a truth commission, but said it would be catastrophic to grant amnesties on either side before the commission did its work.
"The UN totally rejects any amnesties for very serious offences - genocide, war crimes, crimes against humanity - and certainly war crimes here would be clearly applicable," she told the BBC.
She made clear at a news conference that people on both sides should be punished.
"There should be prosecutions of those most responsible for these levels of gross violations of human rights, disappearances, killings, and torture," she told reporters in Kathmandu.
Ms Arbour did not say prosecutions had to happen immediately, nor did she indicate what kind of tribunal should deliver justice. The International Criminal Court has no jurisdiction in Nepal.
She added that post-conflict political environments are very fragile but "justice should not be held hostage" to that.
The UN says more than 600 people who disappeared during the insurgency are still missing and during her trip Ms Arbour met many such families.
She said the families were enduring "terrible suffering" and criticised the government and Maoists for launching "perfunctory investigations".
"Frankly it's an additional insult to them to have a system that is totally dismissive, totally unresponsive to their quest for the truth, for answers," she told the BBC.
She also said that many a times information provided by the government to human rights monitors were found not credible, while the Maoists were reluctant to cooperate.
Ms Arbour also expressed "great concern" for the recent violence in the south-eastern town of Lahan, where five people, including a 16-year-old boy, have been killed in unrest since Friday.
"Now we see what the conflict was hiding - which is much more chronic violations such as discrimination on a very large scale of all kinds of minority groups." Since a ceasefire between the Maoists and security forces began last April there has been only one inquiry commission that has allocated blame.
It pronounced King Gyanendra and 200 other people responsible for suppressing the huge April demonstrations in which more than 20 people died and thousands were injured.