Rwanda's intelligence chief has been arrested in the UK in relation to alleged war crimes, Scotland Yard said.
Karenzi Karake was detained by the Metropolitan Police's extradition unit on behalf of the authorities in Spain, where he is wanted over alleged crimes against civilians.
The 54-year-old director-general of Rwanda's national intelligence and security services was held at Heathrow Airport on Saturday morning.
He appeared at Westminster Magistrates' Court in London and was remanded in custody until Thursday.
A Met spokesman said Karake appeared in court after being arrested on a European Arrest Warrant on behalf of the authorities in Spain "where he is wanted in connection with war crimes against civilians".
"He was remanded in custody to reappear at the court on Thursday, June 25."
The BBC reported that Karake is accused of ordering massacres while head of military intelligence in the wake of the 1994 Rwanda genocide.
He is also accused of ordering the killing of three Spanish nationals working for aid charity Medicos del Mundo.