French authorities are believed to have arrested the alleged gunman who shot a photographer at the offices of the daily newspaper Libération before opening fire outside French bank Societe Generale in the La Defense business district.

According to police sources cited by Le Parisien, the suspect was tracked down after a massive manhunt. He was last seen after he forced a driver to take him to Champs-Elysées where he disappeared into a metro station.

Police officially denied it had apprehended the suspect.

The man was described as "calm and determined", aged between 35 and 45, with European features and shaven salt-and-pepper-hair.

In a fresh photo, taken from a CCTV camera in the Concorde metro station, the suspect wears a red jacket and a beige cap - different clothes from the long green coat and the bullet-proof vest he was wearing on Monday.

Interior minister Manuel Valls said that authorities had been working on the DNA of the suspect, which was found in the hijacked car and on the used cartridges recovered at Libération HQ.

The victim, a 23-year-old originally from the southern city of Toulon, was "still critical", according to Libération executive Nicolas Demorand but "in a slightly better state" after undergoing hospital treatment.

He was on his first day of work as assistant for the magazine Next.

The shooter entered the Libération office on Monday morning armed with a hunting rifle and fired two shots before fleeing. The photographer was hit in the thorax and in the stomach.

The gunman, described as a "tough-looking skinhead in bulletproof vest" by witnesses, fired shots outside the headquarters of French bank Societe Generale.

The incident came three days after a man broke into the Paris HQ of business channel BFMTV and fired several bullets before escaping. No-one was wounded in the incident but the gunman warned a senior editor: "Next time, I will not miss you."