The national commission for complaints against RCMP will investigate four B.C. Mounties accused of watching a sexual encounter between two female detainees without intervening.

The Kamloops officers were accused last month of watching the jail-cell encounter over closed circuit video for seven minutes.

Ian McPhail, interim chairman of the Commission for Public Complaints against the RCMP, said in a release Tuesday that his office had received a formal complaint about the incident.

"In light of this, and the ongoing expressions of public concern as they relate to this matter, I am satisfied that there are reasonable grounds to investigate the circumstances surrounding this incident," he said.

A civilian investigator will now be appointed to review the complaint.

Kamloops RCMP Insp. Yves Lacasse said the detachment welcomes the investigation.

"The CPC's involvement into this investigation will provide an independent analysis of what transpired and we feel this is in the public's best interest," he said.

The male cops were already the subject of both criminal and internal investigation because of what happened on Aug. 18, and have been suspended with pay while the investigations are completed.

Two male civilian guards and one male civilian watch clerk at the Kamloops RCMP detachment are also suspected of watching the encounter and are under investigation by police and the City of Kamloops.

According to police, the two women at the centre of the scandal were arrested separately on suspicion of being drunk in public and causing a disturbance.

Some media outlets have reported that one of the women involved is HIV-positive and did not inform the second woman, but police say they will not comment on those reports because of privacy concerns.

However, the Mounties have confirmed that one of the women is under criminal investigation because of the incident.

The four Mounties at the centre of the jailhouse-sex scandal aren't the only Kamloops RCMP members under investigation or facing allegations of misconduct.

Two more officers are currently under investigation by the Calgary Police Service after the shooting death of Wilbert Bartley on July 30, and another two are awaiting trial on separate assault charges.