Jewish Museum in Brussels
Jewish Museum in Brussels Reuters

Belgium has taken into custody a French national suspected of having helped a compatriot shoot dead four people at the Jewish museum in Brussels last year, prosecutors said Tuesday.

France extradited 28-year-old Mounir Atallah to Belgium on July 1 on a European arrest warrant, Jean-Pascal Thoreau, a spokesman for the federal prosecutor's office, told AFP.

Atallah was later "charged with being the perpetrator, the co-perpetrator or accomplice of a quadruple attack in a terrorist context," Thoreau said without explaining why it took so long to release the news.

The French authorities said Belgian investigating judges want to question Atallah about allegations he may have supplied weapons to Mehdi Nemmouche, who allegedly carried out the massacre in Brussels before being arrested days later in the southern French port city of Marseille.

The allegations were reportedly made by Nacer Bendrer, another resident of Marseille who was handed over to the Belgian authorities in February to face charges of "complicity in a terrorist attack."

Atallah told a court in the southern French city of Aix-en-Provence that he had met briefly with Nemmouche one month before the May 24 attack at the Jewish museum which left four people dead.

He first met Nemmouche in 2010 while the two were in jail in nearby Salon-de-Provence.

Atallah told the French court he was "100 percent innocent" but agreed to be handed over to the Belgian authorities.

At the time of the attack, Nemmouche had returned from Syria where he had been fighting with Islamist extremists and was charged in Belgium with "murder in a terrorist context," officials said.

No date has been set for his trial and Nemmouche has never admitted having carried out the attack, the first of its kind in Brussels in three decades.