DAKAR (AFP) - Senegalese authorities on Friday ordered former Chadian dictator Hissene Habre to appear before a special tribunal to stand trial for torture, war crimes and crimes against humanity.

Once dubbed "Africa's Pinochet", Habre has been in custody in the Senegalese capital Dakar since his arrest in June 2013 at the home he shared with his wife and children.

Rights groups say 40,000 people were killed during the 72-year-old's eight years in power in Chad under a regime marked by fierce repression of his opponents and the targeting of ethnic groups.

The Extraordinary African Chamber, set up by Senegal and the African Union to deal with Habre's case, announced it had made an order of "partial dismissal of proceedings, of impeachment and referral".

"This order refers the accused, Hisseine Habre, to the Extraordinary African Assize Chamber in order to be tried for crimes against humanity, war crimes and the crime of torture," it said in a statement.

The trial, the result of a 19-month investigation by a four-judge panel, is expected to get under way in Senegal in May or June.

Delayed for years by Senegal where Habre has lived since being ousted in 1990, his trial will set a historic precedent as until now African leaders accused of atrocities have only been tried in international courts.

Senegal and the African Union signed an agreement in December 2012 to set up the court to try Habre for the offences.

The AU had mandated Senegal to try Habre in July 2006, but the country stalled the process for years under former president Abdoulaye Wade, who was defeated in 2012 elections.

Habre was also wanted for trial in Belgium on war crimes and crimes against humanity charges after three Belgian nationals of Chadian origin filed a suit in 2000 for arbitrary arrest, mass murder and torture.

'ENORMOUS VICTORY FOR JUSTICE'

Macky Sall, Wade's successor who took office in April 2012, ruled out extraditing Habre to Belgium, which was prepared to try him, vowing to organise a trial in Senegal.

"After so many years, Habre's victims are now on the verge of seeing justice done for what they have endured," Jacqueline Moudeina, lead lawyer for the victims, said in a statement.

"Getting Hissene Habre before a court is an enormous victory for justice."

Reed Brody, counsel for Human Rights Watch (HRW) who has worked with Habre's alleged victims since 1999, said the decision showed it was "possible for victims, with tenacity and perseverance, to bring a dictator to justice".

"A fair and transparent trial for Hissene Habre would now demonstrate that courts in Africa can be empowered to provide justice for African victims of crimes committed in Africa," he added.

The four investigating judges carried out four missions to Chad, HRW said in a statement, interviewing some 2,500 witnesses and victims and analysing thousands of documents.

The trial will be heard by two Senegalese judges and a judge from another African Union member state, who will serve as president of the chamber.

Habre has refused to recognise the legitimacy of the process or participate in the proceedings.

"I have been waiting more than two decades to see Hissene Habre in court," Clement Abaifouta, president of the Association of Victims of the Crimes of Hissene Habre's Regime, was quoted as saying in the HRW statement.

Abaifouta, a political prisoner during Habre's rule, says he was forced to dig mass graves and bury hundreds of other detainees.

"We are finally going to be able to confront our main tormentor and regain our dignity as human beings," he added.