Both security forces and former rebels have been accused of carrying out torture, killings, rapes and forced disappearances during Nepal's decade-long civil war, which ended in 2006 with more than 16,000 people dead.

Authorities have been criticised for failing to adequately probe abuses, with two commissions set up for that purpose in 2015 failing to resolve a single case between them despite over 60,000 complaints.

The government this month presented a bill to amend existing laws relating to war criminals, seven years after the Supreme Court ordered for revisions to stop serious human rights violators from being granted amnesty.

But in a joint statement, Amnesty, Human Rights Watch and other international watchdogs said the proposed amendments would still make it difficult or impossible to prosecute the worst offenders.

"Victims and their families who have waited anxiously for amendments to the law, hoping that their demands for truth and justice will be met, are disappointed," said Mandira Sharma of the International Commission of Jurists.

"Despite the promise of reform, this bill, if implemented as it stands today, would shield many perpetrators from being brought to justice," she added.

Several other aspects of the proposed reforms, including limitations on the right to appeal, also fell short of international standards, according to the joint statement.

Suman Adhikari, whose father was killed by Maoist rebels in 2002, told AFP that the proposed amendments failed to address the concerns of victims.

"We feel that we are not getting justice," he said, adding that the reforms still seemed "designed to grant amnesty to all culprits."

Critics say Nepal's truth and reconciliation process has been poorly designed from the outset and stymied by a lack of funding and political will, with many former Maoist rebels now in government ranks.

Just two convictions related to crimes committed during the civil war crimes have been handed down in civilian courts, one linked to the murder of a teenage girl and another related to the killing of a journalist.