Rwandan intelligence chief Karenzi Karake has been arrested in London, according to BBC Newsnight. Karake is director general of Rwanda's National Intelligence and Security Services.
The Met Police's extradition unit arrested General Karake at Heathrow Airport on Saturday, it is understood. The 54-year-old was remanded in custody until Thursday after appearing before Westminster Magistrates' Court.
Karake is wanted in Spain for war crimes. He is accused of being involved in massacres while head of military intelligence during the 1994 Rwandan genocide. He is also accused of ordering the killing of three Spanish nationals working for Medicos del Mundo.
A Spanish judge indicted Karake for war crimes in 2008, along with 39 other current or former high-ranking Rwandan military officials.
Karake has travelled to the UK several times since the indictment was issued, so his arrest puzzled the Rwandan government. His detention will be vigorously contested, a source told the BBC.
Philip Gourevitch, a leading writer on Rwanda, told Newsnight that Gen Karake's arrest was the equivalent of the head of the UK's MI6 or the US' CIA being arrested. He said the Spanish indictment had been criticised as highly politicised by many, including US diplomats.
Williams Nkurunziza, Rwanda's High Commissioner to the UK, called the arrest "an insult."
"We take strong exception to the suggestion that he's being arrested on war crimes," he told the BBC World Service.
"Any suggestion that any of our 40 leaders are guilty of crimes against humanity is an insult to our collective conscience."