Urging the government to veto the law passed by Peru's Congress a week ago, the experts said international standards "prohibit amnesties or pardons for such grave crimes."

"Peru has a duty to investigate, prosecute and punish gross human rights violations and crimes under international law committed during the conflict," three UN special rapporteurs and other experts said in a statement.

The law, which still needs presidential approval, benefits uniformed personnel accused or convicted of crimes committed during fighting between state forces and the Shining Path and Tupac Amaru rebel groups.

Some 70,000 people were killed during the decades-long unrest, and critics say the legislation would impede access to "justice, truth and reparation for victims."

About 20,000 people remain listed as "disappeared."

Some 156 cases with final judgements and 600 ongoing trials could be affected, according to the UN experts.

The bill was presented by a lawmaker from the right-wing Popular Force party of Keiko Fujimori -- daughter of late former leader Alberto Fujimori who was jailed for atrocities committed on his watch, but released on humanitarian parole in 2023.

"The proposed legislation would prevent the criminal prosecution and condemnation of individuals who committed gross human rights violations during Peru's internal armed conflict," the experts said.

"It would put the State in clear breach of its obligations under international law."