Armed robbers grabbed thousands of pounds in cash and car tax discs from a post office.

Three men ambushed the elderly postmaster as he and his wife opened the branch in Southwick Square, Southwick.

He was threatened with a screwdriver and forced to open the safe at the back of the shop, which also sells trophies and ornaments.

The raiders, wearing grey or dark clothing and hooded tops, left by the rear exit.

They ran towards the car park of the Cricketers pub on Southwick Green.

Police said a substantial number of bank notes and tax discs were stolen in a carefully planned robbery.

Detective Constable Colin O'Hare, of Adur CID, said: "They knew what they were doing and what they wanted to steal. It was a planned operation which has left the elderly postmaster and staff very shaken.

"Somebody will know the identity of these people. It is likely they have talked about committing this crime to friends or family.

"We would like them to come forward and would also ask anyone who has seen a friend or family member with an unusual amount of money, or who has been offered vehicle tax discs for sale, to contact us."

The robbery took place at 8.30am yesterday as other shop-owners in the busy square were opening up for the day.

Michael Forrest, co-owner of Southwick Square Meats, said he saw the postmistress walk by his shop in the morning.

Mr Forrest said: "A few minutes later we heard an alarm going off.

"To be honest we did not think much of it because it is not unusual to hear alarms around here at that time of the morning.

"The next thing we knew, the police were here and they were searching the area with dogs.

"There was no sign of an ambulance so we don't think anyone was hurt."

The post office remained shut for the rest of the day and a notice on the door said: "Closed due to robbery".