Constitution assembly members of an opposition party shout slogans during a meeting at the parliament in Kathmandu on Sunday.

AFP/Kathmandu

Nepal's parliamentary speaker on Sunday announced plans for a vote on a new national constitution to end a political deadlock, sparking fresh anger from opposition lawmakers.

The ruling and opposition parties have spent years locked in a stalemate over the terms of a constitution designed to draw a line under a decade of civil war.

Lawmakers' failure to reach agreement before a deadline last Thursday triggered a political crisis in the country.

Speaker Subash Nembang said he had decided to press ahead with a vote rather than wait until an agreement could be hammered out between the ruling parties and the opposition, which is led by former Maoist rebels.

"I have tried to find a middle way that allows... the Constituent Assembly to move forward, as well as (time to) continue discussions for consensus," said Nembang.

"Taking all things in consideration, I am taking this action," Nembang said of the vote, for which no date has yet been set.

Opposition lawmakers chanted slogans against Sunday's motion to proceed to a vote, which was passed by ruling members and their allies who hold a majority in the parliament.

Maoist chief Pushpa Kamal Dahal, known better as Prachanda, said the move threatened to return the country to conflict and ruled out further talks with the ruling parties unless they abandoned plans for a vote.

"We condemn this regressive and autocratic decision," he said in a statement.

"This decision will deeply polarise national politics... and threatens to push the country towards a new conflict", he said.

Experts said a failure to take opposition views into account risked further deepening hostility between the two camps.

"This is a deeply unfortunate development... Nepal needs a constitution soon, but it's a mistake to draft it without taking the opposition into confidence," said historian and analyst Prashant Jha.

"At a time when trust between parties has collapsed, leading to unruly scenes in parliament, the speaker should be pushing for dialogue so Nepal ends up with a constitution that will last," Jha said.

A key sticking point concerns internal borders, with the opposition pushing for provinces to be created along lines that could favour historically marginalised communities.

Other parties have attacked this model, calling it too divisive and a threat to national unity.

The constitution was intended to conclude a peace process begun in 2006 when Maoist guerrillas entered politics, ending an insurgency that left an estimated 16,000 people dead.

But six prime ministers and two elections later, political infighting has confounded efforts to hammer out a deal, throwing parliament into disarray and crippling the economy.