By Mark Doyle BBC West Africa correspondent in Abidjan

The authorities in Ivory Coast have jailed a group of alleged coup plotters for involvement in the so-called "trial of the black Mercedes".

Six people were sentenced to up to 20 years in prison for taking part in an apparent coup plot in January 2001 which, according to government sources, involved a black limousine being chased away from northern Ivory Coast by government aircraft.

Defence lawyers said the trial was politically motivated.

In the popular imagination, fed by pro-government media, this was a trial that involved a column of cars led by a black Mercedes that originated in a neighbouring northern state and was thwarted from overthrowing the government by the national air force.

This dramatic account is challenged by defence lawyers and opposition sources.

They say the trial is part of a wider malaise which is the continuing tension between the Ivory Coast Government and the mainly Muslim northern-based opposition party, which has inevitable links with countries to the north.

Calm then coup

Until 1999 Ivory Coast was a haven of calm in the turbulent West African region.

But then a coup d'etat changed all that.

The coup was partly caused by the exclusion from a presidential election of the main opposition leader, who is a northern Muslim.

During the last year stability has begun to return, with bodies like the International Monetary Fund encouraging Ivory Coast - a major West African economy - back into the fold of stable countries.

But opposition leaders say this trial is evidence of continuing domestic tension that will not go away until there are completely free elections that include all political parties.