The BBC's south east reporter Peter Whittlesea took this picture of motorists queuing on the approach road to the Channel Tunnel.

He said he had been told that some traffic was being diverted to the Port of Dover.

@onyxparadise tweets, external: And so begins my telephonic journey as I wait on hold to Eurostar customer services to extract my refund...

Eurotunnel freight trains are stationary at Folkestone, Kent.

Charlotte Longstaff emails: I was on the 12:25 train! We were told it would maybe run at 7pm! We are currently in London trying to find a hotel! Was supposed to be going to Paris for a weekend away! Looks like Paris will be booked for another weekend! Very disappointed and scared.

Colin Cooper travelling from Moutiers in France to Reading emails: We've been on the train for about seven hours and have been waiting at Lille for quite a while. Now we've been told we're heading for Paris which is about an hour away. It's the ski train and we're just going home after a week's skiing holiday. We're a bit frustrated but there's not very much we can do about it if there's been a fire. You can either get angry or just sit and wait. I'm not sure why they're taking us back to Paris though as we could have travelled from Lille to get the ferry. We've been told Eurostar will arrange a hotel for us - so I suppose we'll get a night in Paris.

Image source, Reuters

Passengers in France also face delays and have been forced to make alternative arrangements at the Gare du Nord train station in Paris.

BBC transport correspondent Richard Westcott has written a history of the Channel Tunnel in numbers.

BBC correspondent Daniel Boettcher said he had seen a piece of paper which was being handed out to disrupted passengers at St Pancras, London.

He said: "It offers an apology. It says that if passengers have booked for cancelled or delayed trains they can either get a ticket refund, or a free exchange."

Lorries have been halted and are now parked at Folkestone, in Kent, following the closure.

Ben Lawton, who was on a freight train inside the tunnel when the fire broke out, has told the BBC News Channel how his train "filled with smoke" before masks dropped from overhead and passengers were then evacuated.

Image source, Peter Whittlesea

The Highways Agency has said junction 11A on the M20, which serves the Eurotunnel, has also been shut.

It said passengers are "advised to expect delays due to an unplanned incident which has closed the tunnels for customers heading from the UK to France".

BBC correspondent Daniel Boettcher, who is at St Pancras International in London, said: "At the moment many people here don't know where they are going to be staying tonight or when they are going to be leaving on their journey."

Image source, PA

The passenger queues at St Pancras, London, have now spilled out onto the streets.

The Eurostar press office says that since 11:00 GMT 26 trains have been cancelled.

Nick Donohoe emails: I work in France and can only get back once a year to see my family and friends. A horrible experience and no information was supplied at the Paris end other than "smoke had caused suspension of all trains this afternoon". No information on what to do about refunds, compensation or even water and food. Horrible experience.

Mike Curtis-Rouse emails: Returning from skiing in Tignes on 0945 Eurostar with friends, situation desperate, running out of olives, mini dips and champagne, Humour remains broadly extant.

BBC south east reporter Peter Whittlesea said: "From the North Downs above the Eurotunnel terminal, stationary freight locomotives can be seen in a line. There is very little activity. However, lorries are being moved in the terminal. Early reports suggest the tunnel will be closed all day.

"But Eurotunnel has in the past operated shuttle service in one tunnel while the other has remained closed. That decision could be made in the coming days if the tunnel itself has been damaged."

Charlotte Abrahams has emailed: We are currently stuck on the French side at Lille! We are all fine, we have wine!