TORONTO - Ontario won't immediately be testing blood, urine or saliva samples taken from motorists suspected of driving while high, which critics warn is stripping police of important new powers that would help them stop impaired drivers.

The government-run centre responsible for the testing isn't accepting any samples under new federal rules - which came into effect Wednesday - because the province is worried it will overburden the system.

"As the projected workload will exceed current capabilities, the Centre of Forensic Sciences will immediately discontinue acceptance of all submissions related to the Drug Evaluation and Classification program until the necessary capabilities are developed," said a memo sent to Ontario Provincial Police by a top bureaucrat at the Ministry of Community Safety and Correctional Services.

The June 30 memo was circulated by the Ontario Progressive Conservatives, who said they received it from the federal Conservatives.

The new rules - passed in February as part of the Conservatives' crime omnibus legislation Bill C-2 - impose tougher penalties for all impaired drivers and make it a criminal offence to refuse a roadside sobriety test.

Police can also compel suspected drug-impaired drivers to give a blood, urine or saliva sample for analysis, which drivers could previously refuse.

The Ontario government is sending the wrong message to impaired drivers who are getting away with a serious crime, said Margaret Miller, national director of Mothers Against Drunk Driving Canada.

"Why was it left so late? Why is this concern just coming out now?" she said in an interview from Shubenacadie, N.S.

"It's very unfortunate because it sends a signal out there that impaired driving isn't a priority for them. If there was all of a sudden a rush on sexual assault cases, would they stop doing the testing?"

If samples aren't tested, the police won't have the evidence they need to put impaired drivers behind bars, said provincial Conservative Garfield Dunlop.

"I think the Ontario government has dropped the ball on this badly," he said from Midland, Ont.

"They should have identified this a long time ago, back in early March or April, and said we wouldn't be able to handle it at that time."

The OPP already has officers who can administer the tests but others are still being trained, said spokesman Sgt. Pierre Chamberland.

But he wouldn't speculate on how the move will affect potential prosecutions of drug-impaired drivers.

"It's a work in progress and eventually everything will fall into place and it will just become a standard practice that we incorporate in everyday policing," he said.

The province notified Ottawa last November that it would need at least 18 months to implement the new rules, due to "significant operational, capacity and resources challenges," said Laura Blondeau, a spokeswoman for Minister of Community Safety and Correctional Services Rick Bartolucci.

Quebec also indicated that it faced similar challenges, she said.

"We fully support Bill C-2, but police need specific training and equipment to fully implement that legislation, so this has financial and human resource implications for the province," she said.

"We're hoping that the feds will support these efforts with appropriate funding."

A spokesman for Justice Minister Rob Nicholson was not immediately available for comment.