The provincially appointed Office of the Independent Police Review Director will examine police conduct during the G20 summit in Toronto. (Canadian Press)

Ontario police forces that took part in June's G20 security operation in Toronto will be investigated by the Office of the Independent Police Review Director.

Gerry McNeilly, the head of the provincial agency, said Thursday the inquiry will look into the more than 275 complaints his office has received about police behaviour during the summit June 26-27.

Police have been accused of illegal searches and unlawful arrests.

McNeilly said the review will include all Ontario police forces that were involved in the summit, but not the RCMP or other outside forces.

An investigation is necessary because of the volume of complaints and the systemic issues raised since the G20 summit, he indicated.

"The review will investigate common issues arising from complaints against police during the G20 summit," McNeilly said in a statement. "I can ensure that these issues are investigated thoroughly and in a way that is accountable, transparent, efficient and fair to both the public and the police."

The investigation will also examine the detention centre in Toronto's east end where hundreds of detainees were housed.

McNeilly intends to use the powers of his office to subpoena witnesses, including front-line officers — possibly even Chief Bill Blair of the Toronto police.

The investigation will not be held in public, but McNeilly said he hopes to be able to hold at least one public session.

The OIPRD was established less than a year ago by the province to "provide an objective, impartial office to accept, process and oversee the investigation of public complaints against Ontario’s police."

Also on Thursday the Toronto Police Services Board voted to plow ahead with its own review of events surrounding the G20 summit. The board and Blair promised to co-operate in the investigation.