Rio de Janeiro: A Brazilian man accused of stabbing a woman to death in a Rio suburb has confessed to having murdered 41 people, almost all of them women, "for the fun of it", police say.

"He wanted to kill women - white women, not black ones. He followed the victims, studying them closely before committing the crimes," said police commissioner Pedro Henrique Medina.

The man was identified as Sailson Jose das Gracas, a 26-year-old whom police describe as a psychopath, who says he became addicted to murder.

Gracas says he murdered 37 women, three men and a two-year-old child over a nine-year killing spree, explaining he killed the child because he feared it would cry and attract neighbours' attention.