Abdelhamid Abaaoud, who is also said to be associated with foiled train attack in August, has been linked to one of the Paris suicide bombers.
After thwarted attack in August, rail security officers will now be able to deny travel permission to anyone who refuses luggage search.
Police dismissed terror motive in attack on Spencer Stone, 25, who in August disarmed a gunman on an Amsterdam-Paris express.
Internal probe finds staff on Thalys train, accused of leaving passengers to deal alone with gunman, had in fact showed "best possible" reaction.
Interior ministers hold security summit in Paris to formulate co-ordinated response to threat of an atrocity on Europe’s rail networks.
The man arrested after a thwarted attack on a train last Friday was known to intelligence agencies in several countries, including France. Yet Ayoub El-Khazzani, 25, was still able to board a busy Paris-bound train after acquiring an assault rifle and ammunition. Michel Deléan and Louise Fessard ask if European secret services again let a potential terrorist through the net – or whether surveillance on so many potential suspects is simply impossible.
François Hollande said that Friday's train attack could have resulted in 'monstrous carnage' without the courage of several passengers.
Three US passengers who disarmed Thalys gunman said survival instinct drove them, that assailant appeared untrained and events felt 'very unreal'.
Moroccan national Ayoub El-Khazzani, 25, identified by his fingerprints, claims robbery was the motive of his attack on passengers of Thalys train.
The images, filmed by one of three US men who overpowered the gunman, shows him trussed inside the carriage and his bundle of weapons.
Arrested gunman's given identity is that of a 26-year-old Moroccan known to Spanish, French authorities for links to radical Islamist movement.
One passenger said he heard 'click-click-click' like 'a toy' before a man jumped on the gunman, the whole sequence lasting '15 seconds'.
The three young men, two of whom are servicemen, restrained the gunman who had begun shooting in a carriage of the train carrying 554 passengers.
Three people were wounded, one seriously, after a man with Kalashnikov, pistol and knife was overpowered and arrested on the Thalys train in France.