A knife-wielding robber has struck at a Lincoln betting shop.

And this is just the latest in a string of similar armed robberies in the city area.

A female employee at the Tote betting shop in St Mary's Street was threatened at knife-point by the offender.

The robbery happened on Friday at about 7.25pm.

Two days earlier, a Spar shop in Washingborough was robbed and a member of staff was threatened.

And in November there were three similar crimes within a week.

Lincolnshire Police spokesman Dick Holmes said that during the latest incident a man entered the Tote Sport bookmakers and threatened a woman employee with a knife and demanded cash.

"He was handed some money from the cash register," he said.

"The victim was shaken up by the experience but otherwise unharmed."

The criminal is described as white, in his 40s and about 5ft 8in.

He was wearing a blue, mid-length coat, dark trousers and a grey wool hat.

There was a cream or white scarf over his face and he was also wearing silver rimmed glasses."

If anybody has any information about the Tote robbery they are asked to contact Detective Sergeant Jen Waddington on (01522) 882222 with incident number 374 of December 11.

Alternatively, phone Crimestoppers anonymously on (0800) 555111.