French police have arrested a suspect over the shooting last week at the Brussels Jewish Museum who apparently has ties to jihadi elements in Syria, local media reported on Sunday.

French citizen Mehdi Nemmouche, 29, was arrested Friday at a routine customs inspection at the Saint-Charles bus station in Marseilles, while he was on a bus from Amsterdam via Brussels.

Nemmouche had in his possession an AK-47 Kalashnikov rifle, the same type used by the Brussels shooter, a GoPro portable camera, and ammunition and a revolver, also similar to those used in the shooting.

Among his packed clothes, Nemmouche had a baseball cap that resembled that worn by the shooter seen on CCTV footage of the attack. Local media also reported that he had in his bag press clippings about the Brussels Jewish museum shooting. Three people were killed in the May 24 attack, included a French national and Israeli couple Miriam and Emanuel Riva. A Belgian museum employee was critically wounded.

Nemmouche, a resident of the city of Roubaix, was known to French security services and is suspected to have traveled to Syria to train and fight with jihadist elements in 2013, returning only in March 2014, Le Figaro reported. Police suspect he may have turned to radical Islam during a jail sentence for robbery, which he served in 2012, La Figaro reported.

Sources involved in the investigation said that Israeli officials were notified as soon as suspicions arose that Nemmouche could be tied to the Brussels shooting. Suspicions against him grew stronger after it became clear that he had links to Syria.

This was the first time investigators have revealed that a handgun was used in the shooting in addition to the assault rifle. It is not clear why he used two weapons.

Sources said that the use of the second weapon was kept mum from the media in the aftermath of the shooting for reasons pertaining to the investigation. A source said that Nemmouche had displayed a mixture of "professionalism and stupidity," after smoothly implementing a murder and then carrying around the weapons involved.

Nemmouche kept silent for the first 24 hours of his detention, it was reported on La Figaro. His custody, which started mid-day on Friday, can last 96 hours, until Tuesday. If investigators decide to deem the suspect an imminent terrorist threat, his arrest can be extended up to 144 hours, until Thursday, AFP reported.

Hollande: Jihadists mustn't return to Europe

French President Francois Hollande congratulated the police on the arrest, and urged all governments to mobilize and keep jihadi elements from returning to Europe, La Figaro reported.

"We will monitor those jihadists and make sure that when they come back from a fight that is not theirs, and that is definitely not ours ... to make sure that when they come back they cannot do any harm," Hollande was cited by Reuters as saying.

The message "to these jihadists is that we will fight them, we will fight them and we will fight them," he said.

Hollande has said previously the attack was motivated by anti-Semitism.

"This is a relief," Joel Rubinfeld, head of the Belgian League against Anti-Semitism told BFM TV after receiving confirmation of the news, Reuters reported.

"But this is also worrying us ... it is is crucial that countries who have citizens who have gone to Syria take all necessary measures to make sure this does not happen again."

A spokesman for the Belgian prosecutor's office Eric Van der Spyt said Sunday the wounded Belgian victim was still in life-threatening condition. The prosecutor was to hold a press conference on the arrest in France later Sunday.

The shooting is being treated in Brussels as a probable terrorist attack. "The analysis of the camera images shows that we are dealing with an individual acting in cold blood and who is very determined in his actions," Ine Van Wymersch, a spokeswoman for the Brussels prosecution office, told journalists in the Belgian capital.

The Syrian civil war has drawn hundreds of European Muslims so far. French authorities said in February that more than 600 French citizens have gone to Syria, are plotting to go or have returned, and more than 20 French citizens have been killed in fighting. As of mid-January, a dozen French adolescents were in Syria or in transit, according to authorities.

Open gallery view Image of the shooter taken from the video of a security camera at the Jewish museum in Brussels. Credit: Reuters