Yemen's cabinet has approved a draft law which grants President Ali Abdullah Saleh immunity from prosecution as part of a Gulf-brokered transition deal.
The law would give amnesty to Mr Saleh and his aides in "all government, civil and military departments" during his 33-year rule, state media said.
It is still to be approved by the country's parliament.
On Friday, the UN human rights chief criticised the deal, which was signed in November amid a popular uprising.
Navi Pillay said those who committed abuses during a crackdown on the civil unrest unrest must face justice, and that the deal broke international law.
President Saleh has agreed to stand down in February on condition that he and his family are granted immunity from prosecution.
The proposed law, which was drafted by a national unity cabinet led by the opposition, includes all who worked with Mr Saleh and "applies to all acts committed before it is issued", state news agency Saba reported.
Activists say that the country's Revolutionary Guards, run by Mr Saleh's son, were behind the majority of attacks on anti-government protesters.
Those angry with the deal have taken to the streets in recent weeks, demanding the leader and his relatives are put on trial.
On Friday, Ms Pillay said she had been "closely following" the parliamentary debate and said the amnesty would "violate Yemen's international human rights obligations".
"International law and the UN policy are clear on the matter: amnesties are not permissible if they prevent the prosecution of individuals who may be criminally responsible for international crimes including war crimes, crimes against humanity, genocide, and gross violations of human rights," she said.
"Based on information we have gathered, there is reason to believe that some of these crimes were committed in Yemen during the period for which an amnesty is under consideration," she said, without naming any potential suspects.
Yemen's anti-government protests began in January 2011 amid the wave of regional uprisings. Hundreds of people were killed and thousands injured as security forces cracked down on the unrest.
Under mounting pressure, Mr Saleh signed an agreement on 23 November under which he ceded power to his Vice-President Abdrabbuh Mansour Hadi, while the opposition set up a national unity government.
He will stand down ahead of elections scheduled for 21 February.
The transition agreement was brokered by Yemen's Arab neighbours and backed by the US, the EU and the UN.