Eurostar passengers travelling within the Schengen Area (Brussels–Lille and Brussels–Calais; Lille–Calais trips are not allowed by Eurostar) pass through a separate corridor in Brussels bypassing border checks, and enter the preallocated cars of the train, which are reserved for these passengers. This arrangement was set up after numerous illegal immigrants entered the UK without the right to do so, by buying a ticket from Brussels to Lille or Calais but remaining on the train until London – an issue exacerbated by Belgian police threatening to arrest UK Border Agency staff at Brussels-Midi if they tried to prevent passengers whom they suspected of attempting to exploit this loophole from boarding Eurostar trains.[108] Travel from Calais or Lille towards Brussels has no border or security control.