(VOVworld)  - The European Union has said it will not change Europe's passport-free system of travel despite mounting pressure over an attack on a multinational rail line and a large influx of migrants into the EU.

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 (Photo:home.bt.com)

The Schengen agreement allows travel without border checks between 22 EU member countries plus Iceland, Liechtenstein, Norway, and Switzerland.

On Monday, EU Commission spokesman Christian Wigand said that Schengen is non-negotiable and the Commission has no intention of changing it. 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.

Earlier Belgium's Prime Minister Charles Michel said the rulebook might have to be re-examined if police are not able to provide sufficient security for travelers. Germany has called for measures to prevent migrants traveling unchecked throughout Europe and French police have bolstered checks on the border with Italy since June when hundreds of migrants waited to cross. Austria and Hungary have also beefed up border security.