A special African Union court said Thursday it will rule on April 27 on an appeal on behalf of Chad's former president Hissene Habre against a life sentence for war crimes and crimes against humanity.

Extraordinary African Chambers, a body created by Senegal and the African Union (AU), sentenced Habre in May to life behind bars, an unprecedented ruling seen as a blow to the impunity long enjoyed by repressive rulers.

Court-appointed lawyers acting for Habre launched an appeal on his behalf Monday, even though the 74-year-old ex-dictator has refused to recognise the court's authority.

Proceedings have continued in Habre's absence, and the court will announce its verdict on April 27, appeal court president Wafi Ougadeye said.

The verdict will be final. If his conviction is upheld, Habre will serve his sentence in Senegal or in another AU country.

The May decision brought closure for relatives of up to 40,000 people killed and many more kidnapped, raped or tortured during Habre's time as president.

Habre fled to Senegal after his 1990 ouster by Chad's current President Idriss Deby, and for more than 20 years lived freely in an upmarket Dakar suburb with his wife and children.