Detectives are hunting for a man they believe was responsible for robbing two petrol stations at knife-point in the Borehamwood area over the past week.

The Total service station in Allum Lane, Elstree, was robbed on Tuesday night, and the Murco station in St Albans Road, South Mimms, was struck on Thursday last week.

The robber escaped with cash and cigarettes from both premises after appearing with a knife, which he held to the stomach of a cashier at the South Mimms station.

During the latest incident, the man walked into the Total service station at around 8.30pm on Tuesday and escaped with cash, cigarettes and telephone cards.

Two staff were on duty at the time, although one was taking some rubbish out when the man, who was white and around 5ft 6ins tall, walked in.

A 29-year-old male assistant who was behind the till said: 'He had got quite a big knife and he told me not to move, which I didn't, and not to touch the panic button.'

Police believe the man ran into Deacons Hill and are keen to speak to a customer who told staff he saw him drive off in a blue Audi car.

Following the incident at South Mimms, at 7pm on Thursday, which followed a similar robbery at the same service station on June 26, the man fled on foot into nearby fields.

The robber is described as aged around 30 with short fair hair and wore a baseball cap and a blue top on both occasions. In South Mimms he wore jeans, and in Elstree he had white trousers.

The Murco service station is offering a £5,000 reward for any information which leads to an arrest and conviction. Anyone with information is asked to call police on 0208 905 1212.