The Channel Tunnel has been shut and services through it suspended after migrants caused chaos in Calais by attempting to board UK-bound trucks.
Eurotunnel's through-tunnel shuttle services were suspended, while high-speed train company Eurostar announced mid-afternoon that services were being cancelled for the rest of the day.
Three trains stuck outside the tunnel on the English side had to return to St Pancras in London while other trains on the French side were taken back to Paris and Brussels.
Eurostar advised passengers not to go to stations.
The trouble began as migrants tried to to exploit wildcat strike action by French ferry workers.
Lorry drivers forced to slow or stop due to queuing traffic on approaches to the northern French port were faced with migrants attempting to clamber on board.
Migrants were seen walking by the sides of motorways looking for opportunities to jump on to lorries heading to the Port for Dover.
More problems ensued as French ferry workers striking over fears they will lose their jobs next month then trespassed on to Eurotunnel tracks, forcing services to be aborted.
High-speed train company Eurostar said: "They have broken into the tunnel and the tunnel is shut."