DAKAR, August 18, 2008 (AFP) - Rights groups Monday urged Senegal to try former Chadian dictator Hissene Habre for war crimes after its justice minister said a conviction in Chad on similar charges could derail a planned trial here.

Justice Minister Madicke Niang said on Sunday that if Habre had already been convicted for the same crimes in his native Chad, then 'he can no longer be judged in any jurisdiction in the world'.

A court in Ndjamena last week condemned the former president to death in absentia for 'attacking the security of the state,' despite him facing charges in Senegal, his refuge since 1991.

But a coalition of rights groups, including Human Rights Watch, said the conviction 'should not have the slightest affect on Senegal's obligations to try Hissene Habre, conforming to its international commitments and a mandate from the African Union.'

Friday's trial verdict 'related to Hissene Habre's involvement with rebel movements which attacked Ndjamena in February 2008. They are not therefore the same charges for which Hissene Habre is being prosecuted in Senegal,' the rights groups said in a statement.

'We call on Senegal to rapidly prepare the case for trial on the charges of crimes against humanity against Hisene Habre so that his victims, who have waited 18 years, will finally get justice.'

The Ndjamena court also sentenced 11 Chadian rebel leaders to death in absentia on the same charges as Habre, namely for attacking the 'constitutional order and the integrity and security of the territory.'

Niang said on Sunday the death sentence passed in Chad had taken Senegalese authorities by surprise, as they had no knowledge of the Ndjamena trial.

Habre was toppled from power in 1990 and eventually fled to Senegal after an eight-year reign during which thousands of Chadians were allegedly tortured.

An official truth commission report in 1992 accused Habre's regime of committing some 40,000 political murders.

Senegal's parliament last month approved a constitutional change allowing its courts to lift the statute of limitations and prosecute past crimes against humanity, clearing the way to try Habre.