The International Court of Justice (ICJ) has ordered Senegal to prosecute the former Chadian leader Hissene Habre on torture charges "without further delay" if the country does not extradite him to Belgium.
"The court finds, unanimously, that the Republic of Senegal must, without further delay, submit the case of Mr Hissene Habre to its competent authorities for the purpose of prosecution, if it does not extradite him," the ICJ ruled on Friday after a request by Belgium.
The ICJ ruled on Friday that Senegal has breached the UN's torture convention by failing to prosecute Habre.
According to a commission of inquiry in Chad, the eight-year Habre regime was responsible for more than 40,000 deaths among political opponents and certain ethnic groups.
The former leader is accused of torturing hundreds of his opponents to death during his 1982-1990 rule in the Central African nation before fleeing to Senegal, where he now lives in exile.
Brussels issued an arrest warrant against Habre in 2005, after a Belgian of Chadian origin filed a complaint against him in 2000 under Belgium's "universal competence" law.
The law allows those accused of crimes under international law that have affected Belgians to be tried in Belgium.
Brussels has since filed several unsuccessful extradition requests to bring Habre to Belgium on charges including crimes against humanity, war crimes and torture.