TORONTO -- Ontario's governing Liberals are standing by a decision to award an $81-million private security contract for Toronto's 2015 Pan Am Games to an American company.

They say the Ontario Provincial Police looked at all the bids and decided Contemporary Security Canada best met the requirements.

But the opposition parties are questioning why they passed over an Ontario-based company whose bid was reportedly $14 million lower.

The OPP say they followed all the rules and most of the security guards hired for the Pan Am Games are expected to come from Ontario.

The Liberals point out that CSC has experience in similar large-scale events, including the Olympics, and the cost of the contract falls within their budget for private security.

But the Progressive Conservatives say that kind of experience isn't needed when all the guards will be providing is basic security at each venue.

"These guards in Ontario and Toronto are perfectly capable of providing that basic service to keep the athletes and spectators safe, without going outside of the country for that sort of service," said critic Rod Jackson.

"Especially at a premium of $14 million."

CSC -- a subsidiary of an international security firm -- is headquartered in Vancouver, B.C., and is licensed to operate in Ontario, the OPP said.

The OPP is leading the Integrated Security Unit, which also includes Toronto, Hamilton, Durham Region, Peel Region, York Region, Niagara Region, Halton Region and South Simcoe police services, as well as the RCMP.

Private security is needed at the Games so that sworn police officers can be used where their skills and qualifications are most needed, the OPP said in a March 14 release announcing the contract.

The Liberals have been under fire for the rising security costs for the Games, saying the original $113-million estimate was just a "place holder" number and the latest estimate of $239 million could go higher.

The Games will take place at 34 different competition venues in southern Ontario, from Niagara in the south to Orillia in the north, running from July 7 to 26, followed by the Parapan Am Games Aug. 7 to 15.

The total budget for the Games is now estimated at $2.5 billion.