KATHMANDU, Dec 29 (Reuters) - The first group of U.N. arms monitors has arrived in Nepal to manage the weapons of Maoist guerrillas and the government army as part of a peace deal between the two sides, a top U.N. envoy said on Friday. Ian Martin, personal representative of the U.N. secretary-general to the Himalayan nation's peace process, said six monitors arrived on Thursday and they would be part of a team of around 35 people pledged by the world body. "A first task will be registration, initially of weapons and then of combatants," Martin told reporters. "They will be operational from Jan. 7." The U.N. says a full monitoring mission will take some time to be in place and has not set a deadline. Last month, the government and the Maoists signed a landmark peace deal declaring an end to a decade-old revolt in which more than 13,000 people have been killed. Under the deal, the Maoists are supposed to join an interim government after locking their arms up with the U.N. which will also supervise an equal number of arms to be surrendered by the government army. The interim administration is to oversee elections planned in June 2007 for an assembly to map the country's political future and decide the fate of the monarchy which the Maoists want abolished.