Police are to appeal the discharge without conviction of Losi Filipo.

Filipo, 18, was last month discharged without conviction for an attack that occurred in central Wellington in October 2015.

LISTEN ABOVE: Wellington barrister Robert Lithgow QC speaks with Chris Lynch

He was charged with assaulting Kelsey Odell, 22, her boyfriend Hayden Williams, 22, Greg Morgan, 21, and Olivia Samuels, 22.

The sentence caused an outcry from Filipo's victims and other members of the public, who say Filipo should be convicted.

SEE ALSO: Losi Filipo agrees to terminate contract with Wellington Rugby

In a media statement, the Crown Law Office said the Solicitor-General had reviewed the matter.

“Approval has been given to the Police to file an application for leave to appeal, on a question of law, against the decision to discharge Mr Filipo without conviction.

“That application has now been filed in the Wellington High Court.”

Karen Odell, mother of assault victim Kelsey Odell, said they're now preparing the kids for court.

"My gosh. All the parents are just ecstatic at the moment. This is all we wanted in the first place."

Odell said they have to find out what happens from here and get some legal advice.

SEE ALSO: Solicitor General 'looking into' Filipo discharge

The confirmation of an appeal was also applauded by Bob McCoskrie, director of the conservative lobby group Family First NZ.

“This offender-friendly sentence sent a dangerous message that we don’t value the protection of victims and the safety of the public in a case that involved significant violence towards both males and females,” he said.

“This is not about revenge as some will suggest. This is about an appropriate sentence which reflects the gravity of the crime.”

Wellington Rugby terminated Filipo's contract earlier this week.