A teenage girl who smashed a bottle over another girl's head and stole her mobile phone has been given a 12-month sentence.

Croydon Crown Court heard the attack was the culmination of a feud between the two girls, who cannot be named because of their age.

The assault took place outside Tesco in Thornton Heath in January.

Julius Capon, prosecuting, said the girls had never been friends and there had been previous trouble between them.

The 15-year-old was sentenced to 12 months' detention after admitting a charge of causing grievous bodily harm and robbery.

Abigail Penny, defending, said the girl had believed unpleasant comments had been made against.

"She now fully accepts that her behaviour was wrong," Ms Penny added.

Judge Cedric Joseph told the girl, who had a previous conviction for robbery: "This was a thoroughly nasty robbery and wounding. You deliberately broke a bottle and attacked this 16-year-old girl, striking her in the face with the bottle and causing a nasty injury."