The Confederation of Passenger Transport (CPT) is warning coach operators to brief their drivers of the need to remain vigilant at all times, avoid leaving the vehicle in any area they feel places it at risk and follow rigidly the prescribed procedure for checking for any evidence of clandestine activity.
It follows incidents of coaches being boarded by migrants in Lille, Brugge and Brussels.
Advice on how to reduce the risks is provided to members by the CPT.