The eight, detained on Tuesday and Wednesday, include the suspected brains of the operation, identified only as Gemal D., 58, who is known to police, the sources said.

Early in January, a team of five or more heavily armed people used explosives to attack an armoured money transporter in Sarrelouis in Germany close to the French border.

One of the transporter’s guards and a policeman were injured in the attack, which also involved gunfire.

The attackers fled in several vehicles and fired shots at German police during a car chase, a document seen by AFP said.

Gemal D. and three others were arrested in the southwestern region of Pyrenees-Orientales, and the others in northern France and the Paris region, they said. All were being questioned by anti-gang investigators.

One source said everybody connected to the robbery was now under arrest.

Ten other suspects have already been apprehended for their part in the heist.

Within hours of the attack, five suspects were arrested near Paris, including two well-known figures in the French gang underworld, a source said.

Abdelkrim Lho, 56, and Loic Deliere, 45, both have convictions for an attack on an armoured money transport in 2000 in which a guard was killed.

Five others, one of them a woman, were apprehended later in January and in February.

The robbers got away with €2.1 million, according to a German police estimate, of which 860,000 euros were recovered during the first waves of arrests.

The rest of the money is still missing.