The United Nations says it has evidence that Burundi's security forces gang-raped women while searching the homes of suspected opposition leaders, BBC News reports.

Security forces separated the women and raped them, the UN said, adding that it had documented 13 cases. Forces also kidnapped, tortured and killed dozens of young men, it said.

Meanwhile, a court has sentenced four generals to life in jail for their part in trying to overthrow President Pierre Nkurunziza in May last year.

Nine other officers were jailed for 30 years and eight soldiers, including drivers and body guards, to five years for their role in the unrest sparked by Nkurunziza's announcement that he would run for a third term.

He secured a third term in disputed elections in July.