Undercover "marshalls" on trains were among plans discussed at high-level emergency talks on rail security
European ministers met in Paris to discuss tougher security measures, including the possibility of metal detectors at entrances. 

Also understood to have been on the agenda was the idea of using full-body scanners for people who try to board at the last minute, training staff to handle weapons, and using undercover "rail marshalls."

The idea is to create psychological comfort by reassuring passengers and leaving potential criminals wondering whether armed personnel are aboard.

But rail operators fear that more screening will bring significant delays and encourage people to use more road transport.
They are also uncomfortable with arming staff.

The meeting came after a heavily-armed man was pinned to the floor by passengers on the Thalys train from Amsterdam to Paris.

French prosecutors have charged Ayoub El-Khazzani, a 25-year-old Moroccan, in connection with the attack.

Questions have been raised about how someone boarded the train with a rifle, 270 rounds of ammunition, a handgun, a box-cutter and petrol.

Before the meeting, French Interior Minister Bernard Cazeneuve said: "We must see if we can put in place a mechanism that allows control at airports, in transportation, in a more co-ordinated manner."

But Libor Lochman, executive director of the European railways umbrella organisation, CER, said it was important not to overreact, adding: "The level of threat from terrorism is different in each EU country, so flexible measures are needed to adapt to changing security threats."

Recommendations from the meeting will be further discussed at an EU transport ministers meeting on 7-8 October.