DETECTIVES investigating four robberies believe they may be linked.

A man has twice used a hammer to threaten staff and an unidentified weapon was used at another raid.

Cash was taken from the till during three of the robberies.

They happened at shops in Newburn, Walbottle, West Denton and Lemington areas of Newcastle.

A police spokesman said: "The man has worn a mask, scarf or hat on each occasion to hide his face.

"None of the staff at the shops have been hurt, although they have obviously been left shocked.

"Anyone with any information or anyone who may have seen anything is asked to contact detectives at Newcastle area command."

At 9.40pm, on October 25, a man threatened staff at Threshers, The Roman Way, West Denton, with a hammer before forcing them to open the till. He took a small amount of money before escaping on a bicycle.

Staff at Costcutters, in Hawthorn Terrace, Walbottle, were threatened by a man on October 26, at 8.05pm. He left the shop with a small amount of money from the till.

At 9.50pm, on November 4, a man threatened staff with a hammer at Riverside Store, Station Road, Newburn, before again taking money from the till.

A staff member at Singh's Store, in Rokeby Street, Lemington, was threatened when a man entered the shop and demanded money on Sunday at 8.45pm. He left empty handed.

The man was in his early 20s, slim, and between 5ft 7in and 6ft.

Anyone with information is asked to call 0191-214 6555, ext 62545.