French news reports are raising questions about a huge explosion last month in a factory in the southern French city of Toulouse. Officials originally said the explosion was an accident. Authorities say they now are investigating the possibility of a terrorist attack.

On September 21, an explosion at the AZF fertilizer plant demolished the factory and caused widespread damage to Toulouse. In the weeks since the explosion, the top prosecutor investigating the case has maintained that it was accidental. But on Thursday, French Environment Minister Yves Cochet, whose office is responsible for industrial safety, said new information suggests the blast might have been the work of terrorists.

During an interview on French television, Mr. Cochet would not say what that information was. But he said French investigators are not ruling out any hypothesis.

In recent days, French news reports raised the possibility the explosion might have been the work of a suicide bomber. The news reports focus on Hassan Jandoubi, a 35-year-old Frenchman of Tunisian extraction whose body, the reports say, was found at the factory.

The media reports say Mr. Jandoubi had been under police surveillance for delinquency and for his suspected attachment to Islamist extremism. Mr. Jandoubi reportedly began working at the Toulouse factory only five days before the explosion occurred.

On Friday, France's Le Figaro newspaper reported Mr. Jandoubi belonged to a gang known as the Taleban, in reference to the movement that rules Afghanistan. The newspaper, citing a document reportedly given to the French Interior Ministry, said the Toulouse group was known locally for its Islamist sympathies.

But the French media also report Mr. Jandoubi's family has adamantly denied the allegations and have threatened to press charges against those spreading what they consider misinformation. And the Reuters news agency reported Friday that France's Interior Ministry still considers an accident the only plausible explanation, at the moment, for the Toulouse explosion.