Serbian lawmakers have voted to introduce life imprisonment without parole for the gravest criminal acts, despite criticism from the Council of Europe's top human rights official.

Parliament on Tuesday approved the changes to the Balkan country's criminal law with 159 votes in the 250-member assembly. Lawmakers from several opposition parties boycotted the vote.

The new legislation envisages life sentence for such acts as the killing or rape of a child or a pregnant woman. It resulted from a petition launched by the father of a teenage girl who was raped and killed in 2014.

The Council of Europe Human Rights Commissioner Dunja Mijatovic has warned that the law is in violation of the European Convention on Human Rights because it does not envisage the possibility of conditional release or sentence review.