Chinese geneticists have been criticised after cloning five monkeys that were deliberately “edited” to be mentally ill.

Welfare concerns have been expressed after the genetically identical macaques showed signs of depression, reduced sleep and “schizophrenia-like behaviours”.

The animals were born with an inoperative BMAL1 gene, which helps regulate the circadian rhythm and was altered using the CRISPR “molecular scissors” editing technique.

Published in the National Science Review, the experiment by the Chinese Academy of Sciences Institute of Neuroscience (CASIN) should enable teams to try out drugs for use on humans with neurological conditions, the authors said.