UPDATE: Eurotunnel trains set to resume this evening - but Eurostar not restarting services tonight
Holidaymakers are facing hours of travel misery after all Eurostar trains were cancelled due to a lorry fire in the Channel Tunnel.
The blaze at the French end of the tunnel saw all services between London and the Continent cancelled for the rest of the day, leaving many trapped in France and others unable to start their trips abroad.
Eurostar said all trains were returning to original stations because the tunnel would be closed until further notice.
In a message posted on its website: "We are sorry but we are unable to run any further trains today because Eurotunnel has been closed due to smoke detected in the north tunnel.
"If you were planning to travel today, we advise you to postpone your journey and not to come to the station."
These photos show the scale of the disruption with enormous queues stretching outside from St Pancras this afternoon.
It was chaos on both sides - with similar scenes reported in Brussels and passengers caught waiting in Paris.
Kent Police said the smoke was caused by a lorry fire. A spokesman said: "A lorry fire has led to the closure of both bores of the Channel Tunnel.
"The fire was at the French end of the tunnel and is being dealt with by the French authorities. There are no reported injuries.
"However, rail passengers are advised to expect significant delays whilst the vehicle is being recovered and fumes are cleared from the tunnels."
One woman said the queue had been told the wait to refund or exchange Eurostar tickets could be more than three hours.
Eurostar's own Twitter account was frantically answering people's questions and advising anyone forced to stay anywhere overnight to keep any receipts for refunds.
In March, hundreds of Eurostar passengers were delayed after a lightning strike triggered a fire in a building close to the entrance to the tunnel in Kent.
Although there was no damage to the track, four trains in and out of England were affected. Three eventually reached their destinations but the fourth, which had been heading to Paris, was forced to turn back to London.
The latest fire comes as security remains heightened following the fatal terror attacks on satirical magazine Charlie Hebdo and a kosher supermarket in Paris last week.