TERRIFIED workers at an Iceland store were held up by a masked raider waving a knife - without realising it was one of their own workmates in disguise.

Adam Mackie, 20, has been jailed for eight years after wrapping a scraf around his face to hide his identity as he robbed his own colleagues at knifepoint.

He held the blade to his "hated" boss' throat - saying he would kill him unless he filled a bag with £1,000 in cash.

But his mask slipped as he tried to escape and duty manager Emlyn Watkins realised he been held-up by one of his own employees at an Iceland store in Caerphilly.

Prosecutor Tony Trigg said: "Mackie repeatedly told the duty manager he would have his throat slit and would be left in a pool of blood.

"It was a clearly terrifying incident involving the use of knives."

Mackie had only worked at the Iceland store in Caerphilly  for five months before the raid.

He armed himself with a knife and went to the store at 4am knowing that there would only be a couple of his colleagues working to stock shelves.

Mackie had "inside knowledge" of where the safe was and how much money would be in it when he carried out the raid in March this year.

Cardiff Crown Court heard how he made Mr Watkins turn the store lights off so passers-by would have no idea what was happening inside.

He frogmarched Mr Watkins - who he had developed a grudge against during his time working at the store - to the safe and threatened to kill him unless he opened it.

But cashier Linda Platt, 55, the only other member of staff on duty, was able to escape, hiding in a locker room where she called 999.

Mackie, of Pen-y-Cae, Caerphilly, was seized by police at the scene. He admitted robbery and was jailed for eight years.

Judge Thomas Crowther QC told him: "You said you hated Mr Watkins and seemed to relish the opportunity to "Give him a kicking".

A 15-year-old boy who was Mackie's accomplice but cannot be named was given two years detention and training.