A CARAVAN fire which caused heavy smoke to drift across a motorway is believed to be arson.

Emergency services were called to Chadwell Road in Stevenage at about 9.20pm on Saturday after reports that a caravan was alight.

Two firefighting crews from Stevenage tackled the blaze, which spread to a hedge and caused smoke to drift over the A1(M) which runs parallel with the road.

A spokesman for the fire service said the fire was out about an hour later, with the cause believed to be deliberate.

No one was hurt.

A police spokesman said the caravan, which was burnt down to its chassis, has been recovered for a forensic examination and that investigations are ongoing.