Passengers were evacuated

Plumes of smoke seen coming from the rear engine of the 0703 GMT from London Paddington to Manchester were actually dust, according to Virgin Trains.

The train and most of Didcot Parkway station was evacuated, with other trains prevented from stopping while firefighters investigated the incident.

But the operator has said the smoke was dust blown from the tracks and train by fire extinguishers that had apparently gone off by mistake.

I am not aware there was actually any fire on that train Stephen Knight, Virgin

Stephen Knight, a Virgin Trains spokesman, said: "As the 0703 service approached Didcot its fire bottles - effectively an underfloor fire extinguisher - went off.

"The bottles are very high-pressure fire extinguishers with a heat sensor.

"If the fire bottles go off they discharge gas that dislodges dust from the track and underneath the train, which could give the appearance of smoke.

"I am not aware there was actually any fire on that train."

Virgin Trains earlier said the alert caused "considerable disruption".