KATHMANDU, Dec 19 (Reuters) - The U.N. human rights agency released a list on Friday of 170 people it said had disappeared in one district alone during Nepal's decade-long civil war and urged the Maoist-led government to investigate the cases.

Rights groups say about 13,000 people were killed during the 1996-2006 war between Maoist guerrillas and the military under the Himalayan nation's former monarchy.

Releasing a 99-page report, Richard Bennett, representative of the U.N. human rights commissioner in Nepal, said 156 of the 170 "disappearences" from the Bardiya district between 2001 and 2004 had been blamed on the military, the rest on the rebels.

Bardiya in Nepal's southwest plains was a Maoist heartland during the civil war, which ended two years ago with a peace deal that led to elections for a special assembly in April. The Maoists now lead a coalition government.

Bennett said he told Prime Minister Prachanda, the former guerrilla leader, that Nepal's military must carry out an investigation and that the Maoists must cooperate.

The report was released simultaneously in Geneva, where the U.N. agency was asked why it had taken two years since the end of the war to compile the information.

U.N. human rights spokesman Rupert Colville said there had been a series of ceasefires before the 2006 peace deal and people had been afraid to come forward until they were convinced the final ceasefire was working.

It had also been time-consuming to gather and cross-check data, Colville said, adding it was important for families that the 170 cases be finalised.

"The people they're about may not be still alive, but the cases are still alive, the relatives still don't know what's happened to them," Colville told a news briefing in Geneva. (Reporting by Gopal Sharma in KATHMANDU and Stephanie Nebehay in GENEVA, Editing by Dean Yates)

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