GENEVA At least 87 people including ethnic Masalits were buried in a mass grave in Sudan's West Darfur, the U.N. human rights office said on Thursday, saying it had credible information that the Rapid Support Forces were responsible.

"I condemn in the strongest terms the killing of civilians and hors de combat individuals, and I am further appalled by the callous and disrespectful way the dead, along with their families and communities, were treated," said U.N. High Commissioner for Human Rights Volker Turk in a statement.

He called for a prompt and thorough investigation.

(Reporting by Emma Farge, Editing by Rachel More)