There is "strong evidence" of human rights abuses committed by former Chadian dictator Hissene Habre, the prosecutor of the special court set up to try him in Senegal said on Monday.
Mbacke Fall told a media conference he had asked magistrates to place the 70-year-old in custody after finding "serious and corroborating evidence of war crimes, crimes against humanity and torture" during his eight years in power in Chad, where rights groups say that some 40,000 people were killed under his rule.
Habre spent the night in a police cell in downtown Dakar after his arrest on Sunday at the home he shares with his wife and children, a security source told AFP.
Fall told reporters in Dakar that Habre would be presented on Tuesday before the court which would decide the charges he would face and whether he would be kept in custody.
He added that prosecutors considered Habre to have "prime responsibility for the repression" carried out during his reign in Chad from 1982 to 1990.
It was Habre himself who set up the feared "Directorate of Documentation and Security" which is blamed for torture and executions of his political opponents, Fall said.
This evidence was uncovered during recent missions to Belgium, where proceedings have been opened against Habre following a complaint from a Belgian citizen, and Chad, said the prosecutor.
Fall said investigators had "worked on the basis of documents produced by various sources" in Belgium and Chad, and he announced that he was also seeking the prosecution of five former employees of Habre.
The dictator's regime was marked by fierce repression of his opponents and the targeting of ethnic groups, and in 1990 he fled to Senegal after being ousted by Idris Deby Itno, who remains in power.
Senegal and the African Union signed an agreement in December to set up the court to try Habre for the alleged offences.