Geneva (AFP) - The UN whistleblower who exposed the rape of children by peacekeepers in Africa has quit his post to protest what he sees as the "complete impunity" of those responsible, he announced in an interview Tuesday.

The resignation of Anders Kompass, director of field operations for the UN human rights office (OHCHR), was confirmed by a UN spokesman.

The spokesman said the move had been known about for several weeks and would take effect at the end of August, but he did not give a reason for Kompass' departure.

Speaking to humanitarian news agency IRIN, Kompass said he was leaving because of "the complete impunity for those who have been found to have, in various degrees, abused their authority, together with the unwillingness of the hierarchy to express any regrets for the way they acted towards me".

"This makes it impossible for me to keep working there," he said.

In July 2014, Kompass leaked a confidential UN report on the sexual abuse of children by peacekeepers in the Central African Republic to prosecutors in France -- the former colonial power has a force there -- claiming the UN was taking too long to act.

A study by independent experts released in December 2015 found "gross institutional failure" by the UN in the way it responded to the abuse allegations.

It reported that children as young as nine were encouraged to take part in sex in exchange for food or money in the war-torn CAR.

Kompass was suspended for leaking the internal report on the abuse but the independent study exonerated him, IRIN said.

The Swedish national has worked in Geneva for the United Nations for more than 30 years.

In the latest report by UN Secretary General Ban Ki-moon, there were 68 cases of alleged sexual assault by UN peacekeepers last year, a "net increase" from 2014.

Half the cases were reported in the UN missions to CAR and the Democratic Republic of Congo.

The scandal has outraged rights activists who see Kompass as "a hero for trying to protect abused children, in contrast to other UN officials," said Hillel Neuer, executive director of UN Watch.

The group, which monitors the world body, called for Ban to apologise to Kompass.