Police are today hunting "audacious" robbers who dressed up as police forensics officers to raid a Lincoln jewellers.

Terrified staff at James Usher and Son in Guildhall Street were forced to hand over gold and diamond jewellery to two robbers after being threatened with hammers.

The men were dressed in face masks and white hooded boiler suits which had the words 'police forensics' printed on them.

They are believed to have taken only the most expensive items in the shop before climbing into a getaway car, driven by a third man, which had been parked outside.

The green Vauxhall Astra was abandoned and set on fire in Lindum Terrace a short while later, with the three men fleeing through the Arboretum and jumping into a white Transit-type van to make good their escape.

The robbery happened at 9.50am on Saturday.

Police say they are also looking to speak with a fourth man, who left the jewellers minutes before the robbery took place.

"We are interested in identifying a man who left the jewellers several minutes before the incident took places," explained Detective Sergeant Pete Grayson of Lincoln CID.

"He entered James Usher and Son at 9.45am, and left minutes before the robbery took place. He asked the staff there if they were interested in buying any gold.

"He is a white man, approximately 6ft tall, with short dark hair. We presume he is in his early 20s, and he wore a green T-shirt and some cut-off three quarter length shorts."

Anyone with any information is asked to contact Lincoln CID on 0300 11 0300.

Alternatively, they can contact Crimestoppers anonymously on 0800 555111.