The attacker leapt from a dark corner as the victim, who had spent the evening with friends, walked down Gillett Street in Deepdale at 1.30am on Sunday.

The 17-year-old Ingol boy, who had been on his way to the garage to buy some cigarettes, was pushed against the wall by the robber who demanded: "Give me your money, give me your phone and anything else you've got."

The boy threw his cigarettes and lighter to the floor, as well as his £100 profit, but the robber became agitated, deciding it was not enough.

He pulled a knife handle from his waistband and showed the victim part of the blade and told him: "I'm going to shank you". "Shank" is slang for "stab".

The robber punched the youth in the face and bent down to pick up the cash, allowing the victim to run away from the scene.

But the robber then started to chase him shouting abuse. The ordeal lasted around three minutes.

Det Sgt John Crichton, investigating the robbery, has appealed for anyone with information to come forward.

He said: "Although generally Preston does not have a big knife crime problem, we seem to have had a spate of incidents involving knives in the city recently.

"We desperately need information from the community to enable us to arrest these people who are prepared to carry knives. This robbery could have been a lot more serious. The offender did not seem to have any fear and was prepared to use violence to his own ends.

"The victim was driven around the area by an officer but the offender has not yet been traced."

The robber is described as white, aged 19 to 20, 5ft 8in, wearing a balaclava and a black full tracksuit with thin white and thin red piping down the arm and leg.

Anyone with information should call Preston police on 01772 203203 or Crimestoppers on 0800 555111.

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