A teenage girl suffered a broken nose and cheek bone as she fought off a robber.
The 14-year-old victim was in Preston Park, Brighton, with friends when a 16-year-old girl approached and asked to see her earrings.
She said no but the attacker tried to pull them off, pulled her hair and punched her, sending her to the ground.
The older girl then repeatedly punched and kicked the victim in her face and chest.
She was taken to the Royal Sussex County Hospital, Brighton.
The attacker is white, 5ft 2in, slim with blonde hair tied in a bun and gelled. She was wearing trainers, gold neck chains and a sovereign ring.
Detective Constable Jason Foy said: "There were a number of young people in Preston Park when this assault happened. Please talk to your children and ask them if they saw anything."
The attack happened at about 8pm last Friday and police only released details last night.
Mr Foy can be contacted on 0845 6070999.
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