BRUSSELS (AFP) - The Belgian authorities are questioning staff at a Brussels school attended by one of the Paris attackers whose warnings that he had become worryingly radicalised were missed, press reports said on Saturday (Dec 26).

The reports, based on Flemish language dailies De Morgen and Het Laaste Nieuws, said Bilal Hadfi had been a student at the Annessens-Funck school before going to Syria in February.

Hadfi blew himself up outside the French national stadium in northern Paris during the Nov 13 attacks that left 130 people dead.

The Belga news agency said documents cited in the reports showed that Hadfi's teachers had become concerned at his increasingly radical views, especially his comments over the January attack on French satirical magazine Charlie Hebdo.

The reports said the school informed the education authorities in April that he had gone to Syria but that this information was not then passed on to the police.

While Hadfi's name appeared on a list of suspects compiled by Belgium's anti-terror watchdog, the school's warning only came to light after the attacks, the reports said.

The police are now trying to establish how that happened as they the search for suspects, included the most wanted, Brussels-born Salah Abdeslam, who fled back to the Belgian capital after the attacks.

On Thursday, the authorities charged a ninth person in connection with the attacks.