A Frenchman with suspected ties to Islamic radicals in Syria has been arrested over last week's shooting at the Jewish Museum in Brussels that left four people dead.
The suspect, 29-year-old Mehdi Nemmouche, was arrested on Friday in the southern French city of Marseille.
He was reportedly in possession of a Kalashnikov rifle and a handgun similar to the ones used in the attack on 24 May.
He has been detained on suspicion of murder and attempted murder in connection with a terrorist enterprise, sources told AFP news agency.
An Israeli couple and a Frenchwoman were killed outright during the incident, while the fourth victim, a 24-year-old Belgian man, was left clinically dead.
Authorities had released chilling security camera footage of the gunman, wearing a cap and sunglasses, walking into the museum, removing an automatic rifle from a bag and shooting through a door before making an exit.
Customs officials detained Nemmouche at Marseille's coach station on board a bus arriving from Amsterdam via Brussels.
According to sources close to the investigation, he was carrying a Kalashnikov automatic rifle and a gun with ammunition in his luggage, as well as a miniature video camera.
Originally from Roubaix in northern France, he is believed to have travelled to join Islamist fighters in Syria in 2013, and was known to the French domestic intelligence agency DGSI, the source said.
He is being questioned by the DGSI who can hold him for up to 96 hours, until Tuesday, or 144 hours, to Thursday, if investigators invoke an imminent terrorist threat.