B. Lynn Pascoe, undersecretary general for political affairs, told a gathering in Kathmandu that there is an urgent need to restore trust among political parties so that the twin tasks of drafting a new constitution and integrating and rehabilitating Maoist former fighters progresses.

"I do not need to tell you that over the past two years, the exhilarating feeling of those earlier moments in the peace process has faded," said Pascoe, who arrived in Kathmandu on Wednesday for a two- day visit.

"Progress has slowed and unity has frayed. The Nepali public has become impatient and disappointed, and the feeling is increasingly shared in the international community," he added.

Pascoe noted that over half of countries emerging from protracted civil wars slide back into conflict within the first decade.

"While I am in no way suggesting Nepal is heading down the road of resurgent conflict, I do wish to underscore the vital importance of the issue. The effective integration and rehabilitation of former combatants is one of the most important factors distinguishing those countries that successfully navigate these transitions to peace," he said.

Pascoe termed as unfortunate the fact that Nepal today still has two armies, and no agreed strategy for what to do about this.

"Thousands of former Maoist combatants remain in camps that were intended to last only a few months, under UNMIN monitoring that has also gone on much longer than anticipated," he said, referring to the U.N. Mission in Nepal.

Nepal's peace process started in 2006 when Maoists ended a 10-year war demanding a republic and a new constitution.

A special assembly elected in April 2008 abolished the monarchy, meeting the Maoists' first demand. But in over 21 months since the election, there has been little progress on charting a future course for the Maoist combatants and agreeing on a new constitution.

Nepal was plunged into a political crisis after a coalition government led by Maoist leader Prachanda collapsed last May after his decision to sack the country's army chief was countermanded by the president.

Since then, Maoist participation in the peace process has been lukewarm.

The special assembly has until May 28 this year to promulgate a new constitution and settle the future of former Maoist fighters, both of which look highly unlikely to be done by this deadline.