The European Union has stated that it will not change mainland Europe’s passport-free system of travel.
The decision comes despite pressure to do so amid the thwarted rail attack in France on Friday and a large influx of migrants into the EU.
The Schengen Agreement allows travel without internal border checks between 22 EU member countries plus Iceland, Liechtenstein, Norway and Switzerland.
EU Commission spokesman Christian Wigand said “Schengen is non-negotiable and the commission has no intention of changing it”.
But he said that Schengen rules allow for security to be stepped up by national police as long as actions are targeted and do not substitute for border checks.
Belgian Prime Minister Charles Michel has said the rulebook might have to be re-examined if police are not able to provide sufficient security for travellers.
Unlike airports, international trains in Europe do not have routine identity and baggage checks, apart from the Eurostar train linking the continent to the UK, which is not a Schengen member.