A French court on Thursday dismissed a bid to hold energy giant Total and one of its former bosses responsible for a 2001 chemical plant blast that left 31 people dead.

The court in the southwestern town of Toulouse also ruled that a Total subsidiary Grande Paroisse and its former boss were not responsible for the blast that also injured 2000 and devastated 30 000 homes.

Coming just days after the September 11 attacks in New York, the blast initially sparked fears of that it was a terrorist attack but that theory was later dismissed by investigators who believe it was a deadly accident.

The explosion occurred in a storage warehouse packed with 300 tonnes of ammonium nitrate at the AZF chemical fertiliser plant south of Toulouse owned by Grande Paroisse.

The court acquitted the former boss of the AZF plant Serge Biechlin as well as Grande Paroisse, arguing that there was not enough evidence to show their negligence had caused the blast.

The tribunal also eliminated the Total group and its former head Thierry Desmarest from the case, ruled that a summons against them issued by victims was not admissible.

Since the blast, Grande Paroisse has paid out ?1.954-billion in compensation to more than 20 000 victims, according to Total's figures.

The case, which began in February, was held in a special 1000-seat courtroom to accommodate the more than 1800 civil plaintiffs, 60 lawyers, five judges and two prosecutors involved.