A teenage girl has been convicted of robbery after she photographed herself wearing a balaclava and holding a knife she went on to use in a restaurant robbery.

The 17-year-old girl and her accomplice photographed themselves armed and disguised before robbing a Max hamburger restaurant in Halmstad, southern Sweden, according English news website The Local.

Police recovered the phone the girl used to take the picture. In it, she was holding a 30cm knife.

They stole 2,420 kronor (£230) from the restaurant. A witness told the court that the girl threatened staff and shouted: "Give me the money or I'll stab you".

Police arrested the girls just 47 minutes after the robbery took place. They found a bag filled with money and the phone with the pictures on it.

The teenager claimed the photos were meant to be a joke.

The older of the two girls was convicted of robbery and sent to juvenile detention.

The other girl was too young be charged under Swedish law.