Four years after elections ended centuries of royal rule, lawmakers in Nepal are scrambling to complete a constitution amid widespread doubt that the troubled nation is on the road to lasting peace.

Once a Hindu monarchy, the country has evolved into a secular democracy and the new constitution should be a key step towards healing rifts that led to the bloody 1996-2006 civil war between Maoist rebels and the state.

But with just days to go until the interim charter expires on May 27, deep divisions remain over proposals for the creation of federal states and a new system for governing the impoverished Himalayan nation.

"If the constitution is formally delivered, there will be a large number of people and groups rejecting it," said political commentator Yubaraj Ghimire.

"People won't own it because they and the (parliament) are being totally bypassed by the leaders of the big three parties."

The fate of former Maoist fighters who were living in camps around the country -- one of the biggest obstacles to peace -- -- was resolved in February when many of the ex-rebels were integrated into Nepal's security forces.

But proposals to create states to decentralise government and empower historically marginalised groups have split opinion, with ethnic tensions spiralling into violence.

More than 70 people were arrested in the capital Kathmandu and second city Pokhara this week as striking protesters forced shops to close, warned drivers off the roads and attacked journalists covering the events.

Residents of the country's remote west have endured weeks of strikes by demonstrators demanding their region is not split up, while other groups across Nepal have being striking to demand recognition of their ethnic identity.

Ghimire said there was "no way" that a new constitution -- if agreed by Sunday -- could guarantee stability or peace, and he predicted further unrest if a deal was reached.

"Violence has been legitimised. People have also come to realise that only powerful and organised protests will be responded to by the state," he said.

Nepal's Constituent Assembly was elected in 2008 with a mandate to draft a constitution within two years. Yet lawmakers have been unable to do so because of distrust and differences among the major parties.

Some are calling for the country to be run by a parliament with a ceremonial president while others want a powerful elected president -- the system favoured by the Maoist party that gave way to a national unity government earlier this month.

Several 11th-hour deals have already been required to extend the interim constitution and prevent the assembly being dissolved.

The Supreme Court has ruled that Sunday's deadline must be the last, but the cabinet agreed late Tuesday to ask lawmakers to vote for a fifth extension, this time for three months.

Some analysts have warned of a power vacuum and political crisis if Nepal is left without a constitution, and many see one last extension as the only option.

Prashant Jha, one of Nepal's leading political analysts, has urged parliament to extend the deadline to give party leaders time to engage with groups feeling marginalised by the constitution-writing process.

In a recent commentary in the Kathmandu Post he called for "a short and final extension to solely focus on state restructuring, take into account emerging voices from below, and refine the constitutional text".

Many Nepalis are becoming increasingly frustrated as six years of political stagnation have damaged business, halted improvements in infrastructure and kept the average wage at barely $1.25 a day.

Arun Budhathoki, a 25-year-old student, returned to Kathmandu last year after studying for an international relations degree in England but, like millions of young Nepalis, has been unable to find work.

"A newspaper hired me but after working for two weeks, it refused to pay," he said. "I was shocked and disappointed.

"They want unemployed youths like me to work for free. There's no work culture and they lack professional ethics. My attempts to find a job in NGOs (non-governmental organisations) proved futile.

"The political situation hasn't improved either. Every day there are strikes and politicians wrangle over petty things. I don't see my future here."