Two victims of an assault in Christchurch about 1am on New Year's Day are using social media to try and track down the offenders.

A battered Georgia Fergusson recalls screaming as the blows rained down while she lay in the street during a New Year's Eve attack in Christchurch.

Fergusson, 22, was left with a badly bruised head and face, cuts and bruises to the backs of her arms and a shard of glass in her leg.

Her mother, 47-year-old Michelle Coker, also suffered severe bruising after being hit in the face.

DAVID WALKER/FAIRFAX NZ New Year's celebrations turned violent for Georgia Fergusson, left, when she and her mother, Michelle Coker, were assaulted getting into their car outside the Christchurch Casino.

The pair have both been interviewed by police, who confirmed they were "actively investigating" the incident outside the Christchurch Casino.

Fergusson struggled to hold back tears on Monday as she recalled seeing her mother's battered face after the attack.

The pair became caught up in the incident after Fergusson, who spent the evening out with her boyfriend, was attacked by a woman she said had a "thick, foreign accent".

The couple spent New Year's Eve at the casino's Mashina Lounge and decided to stick around for the midnight countdown, before sorting out a ride home about 1am.

"Everything was normal and fine and I turned around, my mum's pulled up on Victoria St, and there's a woman trying to get in my mother's car.

"I go over and my boyfriend goes over and I say 'hey, this isn't a taxi'."

Her attacker looked at her as she got in the car, before "punching me right in the face".

Fergusson was adamant she did nothing to provoke the woman.

"I was just trying to get in the car and go home."

A flurry of punches then rained down, Fergusson said.

Videos posted on Fergusson's Facebook page show the tailend of the incident.

Coker can be seen repeatedly hitting the woman on top of her daughter in the back and trying to pull her away.

"It's just a blur after that of just being hit, hit, hit, hit and in that process I've gone on to the ground," Fergusson said.

"I don't know if I was knocked out, I have no idea, but it just went on for so long."

Coker became involved as soon as she saw her daughter being hit.

The scene, she said, was "surreal".

"My main focus was get her off Georgia, but in the back of my mind 'don't hit her [the attacker] in the head'," Coker said.

The sight of her mother's blackened eye from a shot to the face was almost too much for Fergusson to bear.

"I didn't know anyone had hit her – I was just like 'oh my god, please no'.

"I just wish it would rewind."

Coker said she and her daughter wanted to know who attacked them, so they could be charged.

Senior Sergeant John Daunton, of the Canterbury District Command Centre, said police were "actively investigating" the incident, but could not confirm whether any arrests had been made.

Police were on foot patrol in the area and attended shortly after, he said.