AN armed robber posing as a workman held a gun to a cashier's head and demanded money from a Skipton supermarket.

The man duped his way into the cash office at Morrisons at 7.20pm on Saturday and the Herald understands that he fled with more than a quarter of a million pounds in cash.

On Wednesday lunchtime three officers in wetsuits searched the culverts surrounding Morrisons. They went in near the entrance to the supermarket and walked in the water until the culvert met Black Walk. They found nothing.

It appears that the masked robber picked his moment carefully, choosing to rob the store at the end of a busy day's trading and on a Lottery day.

He was caught on CCTV cameras entering the store with a briefcase, demanding money from the girl in the cash office, and then leaving through the supermarket's main entrance.

Acting Detective Inspector Pete Martin said a "substantial" amount of money was stolen from the store and appealed for any customers who saw anything suspicious to come forward.

He said that although the man had a handgun no shots were fired. He left the store on foot.

"Thankfully no one was injured on this occasion although the staff member who dealt with the offender was extremely distressed by the incident," he added.

The man is described as white, tall and slim with dark hair. He was wearing a blue top with a black band around the midriff and dark trousers. He was carrying a black briefcase with silver trim.

This is the third armed robbery in three weeks in Craven. On March 2 a man with a gun threatened staff at the Esso Station in Cross Hills and escaped with cash, and on Sunday March 10 masked raiders with a sword stole computers from Landis Lund in Eastburn.

DI Martin said: "We do not believe this robbery is connected with the two previous offences at this stage. Fortunately this type of crime is still rare in this area.

"We would appeal to anyone who was in Morrisons at the time of the offence who has seen this man to contact my officers as soon as possible."

DI Martin said all lines of inquiry were being pursued to catch the robber.

Anyone with information is urged to call Skipton CID on 01756 793377 or Crimestoppers on 0800 555111.