Misery for Eurostar passengers looks set to continue after the operator has said it "had no expectation" of resuming services on Friday.

Thousands of travellers were stranded on Thursday after a fire broke out on the French side of the Channel Tunnel, causing the suspension of all rail services on the undersea route.

Massive queues of cars and lorries built up at Calais ferry terminal as drivers waited to get back to the UK.

Channel Tunnel operators offered motorists a voucher to switch their journey from the Tunnel to boats to Dover - and thousands took the opportunity.

Only a few dozen Britons remained at the Tunnel terminal, some checking into nearby hotels while a few travelling in camper vans made the most of their transport and bedded down for the night in the car park.

Six people suffered minor injuries and dozens needed to be evacuated from the tunnel after the blaze, which started on a lorry on board a freight train travelling from Folkestone to Calais.

In a statement the operator said: "Eurostar does not expect to operate any services tomorrow (Friday) between the UK and the continent."

Around 14 people were treated for smoke inhalation and minor cuts and bruises following the incident which began at approximately 2.55pm UK time.

A lorry transporting the toxic chemical Phenol had left Folkestone but overturned on a truck shuttle and burst into flames around seven miles (11km) inside the tunnel from the Calais side.

Around 50 people, mostly truck drivers, were evacuated as services were suspended in both directions.

A Eurotunnel spokeswoman said none of the company's passenger trains was in the tunnel at the time of the incident.

She added: "The situation is that we're at a complete standstill. We have got services on both sides of the tunnel and they have been stopped. They are at various stations on either side of the tunnel. We are looking at what to do with them. At this stage we don't know how long the incident will last."

Meanwhile, Eurostar said five of its trains were en route when the fire broke out - the 1434 from London to Brussels; the 1530 from London to Paris; the 1459 from Brussels to London; the 1513 from Paris to London and the 1605 from Brussels to London.

They are now returning to the stations where they began their journeys. A total of 2,000 passengers on the trains were affected.

Kent Police have implemented Operation Stack, closing the M20's coastbound carriageway between Junctions 8 and 9 so that lorries can be parked on it. Non-freight traffic was diverted off the M20 at Junction eight on to the A20.

A police spokesman said: "Traffic on the M20 is heavy around Dover and Eurotunnel and drivers are urged to avoid the area unless it is absolutely necessary."

Eurostar said it has implemented a policy of exchange or refund for people who do not want to travel after the incident.

The three tunnels underneath the Channel - two for passengers and one for emergencies and evacuation - are equipped with sophisticated fire detection systems including flame and smoke detectors.

In 1996, the tunnel was severely damaged in a major fire on a shuttle train carrying lorries. That blaze burned for several hours, wrecking the concrete lining and facilities over around half mile of tunnel and causing £200 million worth of damage.

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