A nine-year-old girl who was carrying twins, allegedly after being raped by her stepfather, has undergone an abortion despite complaints from Brazil's Catholic Church.

Police said the stepfather has been jailed since last week.

Abortion is illegal in Brazil, but judges can make exceptions if the mother's life is in danger or if the foetus has no chance of survival.

Fatima Maia, director of the public university hospital where the abortion was performed, said the 15-week-old pregnancy posed a serious risk to the 36-kilogram girl.

"She is very small. Her uterus doesn't have the ability to hold one, let alone two, children," Ms Maia told the newspaper.