Former US president Jimmy Carter called Wednesday for compromises among Nepal's rival political factions to set the country on the road to peace, six years after the end of civil war.

Carter encouraged party leaders to "resolve swiftly all outstanding debates" to allow the drafting of a new constitution in line with a peace accord brokered after the Maoist insurgency ended in 2006.

"The May 2012 constitutional deadline is rapidly approaching. After multiple delays, it is time for Nepals political parties to deliver on their commitments to the Nepali people," he said in an open letter to the people of the Himalayan nation.

"Nepals leaders should seek broadly acceptable compromises in order to promulgate a democratic and inclusive constitution within the given time frame."

In February hundreds of former Maoist fighters began to leave the camps that have housed them since the end of the conflict.

Their departures followed a peace deal struck late last year offering the 19,000 fighters voluntary retirement payoffs, integration into the army, or a rehabilitation package including vocational training.

An overwhelming majority expressed interest in joining the country's national army, while 7,365 of them opted for the 500,000-800,000 rupee ($6,300-$10,200) pay-off.

"At this critical time, I hope that all sides will re-dedicate their energies to successful completion of the peace and constitutional processes and work to uphold the principles of peace, democracy, justice, human rights, inclusion, rule of law, and press freedom encapsulated in the guiding documents of Nepals historic peace process," Carter said.

According to the deal, 6,500 former fighters will be integrated into the national army.

The Maoists fought a decade-long war against the state in which at least 16,000 people died.

The former rebels joined mainstream politics in 2006, going on to win landmark elections two years later and abolishing the country's 240-year-old monarchy.