SHOPKEEPERS are being urged to remain vigilant after a string of thefts from the till.

Police said four incidents had occurred over the past 10 days, including a raid on Monday night at a service station where a female member of staff was assaulted.

The latest theft occurred just last night.

In each case a man has told staff he wanted change and when the till was opened made a grab for the contents.

More than £500 has been stolen.

Detective Sergeant Mark Evans of Blackburn CID said a similar description was given for all four crimes, although he said police were keeping an open mind over the connection.

The first theft occurred at Bargain Booze, Union Road, Oswaldtwistle, on June 16.

Two days later a man struck at Booze Busters in Bolton Road, Blackburn, followed by SJ Worsley Newsagents in Preston New Road, Blackburn, on Saturday.

On Monday night a member of staff at Livesey Service Station in Livesey Branch Road, Blackburn, was assaulted as the raider moved in to snatch from the till. And last night at around 9.30 Booze Busters, Burnley Road, Blackburn, was targeted.

CCTV footage of the thefts is currently being investigated.

DS Evans said: "We want to warn shopowners to be vigilant about a man who comes into their premises asking for change.

"He has assaulted one member of staff and we want to catch him before somebody gets seriously hurt.

"The crimes maybe linked in the way they are carried out and the descriptions given but we are keeping an open mind and are appealing for witnesses."

Anybody with information should contact Crimestoppers on 0800 555 111 or Blackburn CID on 353569.