An outside police force has been brought in to investigate claims that Mounties in northern B.C. beat up a handcuffed teenage girl earlier this month.

Investigators from the Abbotsford Police Department will look into 17-year-old Jamie Haller's claim that she was punched numerous times by officers with the Williams Lake RCMP. They will also investigate allegations that it was Haller who assaulted the Mounties.

"Senior managers in the division felt that, in order to ensure public confidence in the outcomes of the investigation, an independent police agency should be called in." RCMP spokesman Sgt. Rob Vermeulen said in a release Thursday.

Mounties in Williams Lake are also conducting their own investigation into the events.

Haller claims that gang members were chasing her on Sept. 10 when she asked a passerby to call police for help. She says that when officers arrived on scene, they slapped on handcuffs, "roughed" her up and put her in the back of a cruiser rather than helping her.

She admits that she became enraged and started kicking at the window of the police vehicle.

"One guy jumped in and was holding my legs down, the other guy was holding my upper body and he was punching me in the face. I know he must have punched me more than six times," Haller told CTV News.

She was taken into detention at the RCMP detachment and released the next day without charge. Photos said to be taken after the incident show Haller with a black eye, cut lip and significant swelling and bruising on the left side of her face.

The B.C. First Nations Summit, the B.C. Assembly of First Nations and two other native groups say this is just the latest example of how the RCMP and the justice system are mistreating aboriginals.

Assembly Regional Chief Jody Wilson-Raybould says it's time for the province's solicitor general to take a hard look at aboriginal people and the justice system in central and northern B.C.

The BC Civil Liberties Association and First Nations leaders are calling for an independent review of what happened.

With files from The Canadian Press