An Olympic boxer's teenage sister is recovering after she was knocked out at an underage club night.

Lucy Jeffries, 15, the sister of Tony Jeffries who won bronze for Great Britain in 2008, was punched unconscious and left with two black eyes after going to the night for over-15s with friends.

She suffered a bloodied nose, swollen cheeks and bruises on the back of her head in the horrific assault which happened at the Quayside Exchange in High Street East, Sunderland.

She said: “Practically my whole face is bruised. I was knocked out for a few minutes, but I could still feel her punching me in the face.”

Professional boxer Tony, 26, who will compete in London 2012, said he was left horrified when he saw his little sister’s injuries.

He said: “It was horrible, I’ve not seen a boxer’s face in the state hers was in.

"I want mams and dads to realise what can happen at these underage nights.”

Lucy had been on the dance floor when she says a friend of hers accidentally bumped into her attacker and apologised.

Mistaking Lucy for the girl who had knocked into her, she carried out a sustained and unprovoked attack, knocking her to the ground.

After the attack on Thursday night, Lucy, from Silksworth, Sunderland, spent the night and next day in hospital as she had X-rays and doctors examined her face.

She said: “I remember waking up after the attack and my friends were all with me.

“I was told the girl had been kicked out, but a bouncer walked over, looked at me, and walked away again. No one called an ambulance.

"Thankfully, my injuries were not as bad as they could have been.

“My friends took me home and when my mam saw the state of my face, she was devastated.

“She called my brother and his girlfriend Sarah and they took me to hospital and stayed with me.”

Lucy says she had not had any alcohol on the night, confirmed by hospital tests, but that her attacker may have been drinking.

She said: “They were serving alcohol there, but were asking for ID. I’ve spoken to police who’ve said they are going to examine the CCTV footage.

“I’m just waiting for them to get back in touch.”

It is believed the venue had been hired by an events promoter to stage the teen party.

• A 14-year-old girl was arrested in connection with the incident. She has been bailed pending further enquiries.