(Adds U.S., UN comments paras 8-13) By Gopal Sharma KATHMANDU, Jan 19 (Reuters) - Nepal's former Maoist rebels will join an interim government in February, the Himalayan nation's prime minister said, capping a fast-moving peace process that is ending a decade-old civil war. Earlier this week, the Maoists joined an interim parliament, began handing over weapons and dissolved their parallel government and "people's courts" under a November peace pact aimed at ending an insurgency in which over 13,000 people died. "The interim government including the Maoists will be set up in 15-20 days at the latest," Girija Prasad Koirala said on state television on Friday. The interim administration aims to organise elections for a special assembly to prepare a new constitution and decide the future of the monarchy, which the Maoists want abolished. The polls are expected to take place in June. The Maoists began fighting the monarchy in 1996, but declared a ceasefire last year after mass street demonstrations forced King Gyanendra to give up direct rule. The former rebels hope the constituent assembly will end the centuries-old monarchy and lead to establishment of a republic. Koirala said the interim administration would be named after the UN-monitored arms handover. Key donor United States, which has kept the Maoists on its list of terrorist groups, said the arms handover must be completed in an "effective and transparent" manner before the former rebels entered the government. "No partner in a coalition government should expect to retain a private army. Destabilization, mistrust, and insecurity invariably would result," U.S. Ambassador James F. Moriarty said in a statement. U.N. Commissioner for Human Rights Louise Arbour, who began a six-day tour of Nepal on Friday, said promotion of human rights in the transition was a challenge for a country that for years had been immersed in violence and political turmoil. Nepal must end impunity for serious human rights violations and resolve many outstanding cases of disappearances, Arbour told reporters. Rights groups say that hundreds of people, mainly Maoist suspects, disappeared during the conflict. Many are presumed detained and murdered by security forces, according to rights groups. The peace process is not without its problems. Analysts and media reports say the Maoists are still intimidating other political parties in the villages where the former rebels have a strong influence.
