Paris - The trial opened Monday in the southern French city of Toulouse of the former head of the fertilizer manufacturer AZF, for his responsibility in the 2001 explosion of an AZF chemicals factory that killed 30 people and injured some 2,500.

Also on trial in the worst industrial accident in post-war France is a subsidiary of the oil giant Total, which owned the factory. All the accused face charges of manslaughter.

The explosion of 296 tons of ammonium nitrate on September 21, 2001, was so powerful that it registered 3.4 on the open-ended Richter scale and left more than 70,000 people homeless.

Coming only 10 days after the terrorist attacks on New York's World Trade Center and the Pentagon, it was at first feared to have been the work of terrorists.

However, an investigation found that the accident was provoked by the mixing of 250 kilogrammes of ammonium nitrate with another chemical that might have been due to negligence in the storing of the chemicals.

As owner of the factory through its subsidiary, Total has so far paid out nearly 2 billion euros (2.57 billion dollars) in damages related to the accident, but it has always denied legal responsibility and sought to refute the experts' conclusions.

Nearly 3,000 people have presented themselves as plaintiffs in the trial, which will hear more than 1,100 witnesses and is expected to last for four months.

The trial will be the first held in a French criminal court to be filmed. Previously only the trials of accused French war criminals have been put on film. (dpa)