TORONTO - Ontario's health minister is warning pharmacists angry over changes to the drug system not to "hold patients hostage" by withholding services.

Health Minister Deb Matthews says the fight over changes like eliminating so-called "professional allowances" is between the pharmacists and the government -- and patients should be left out of it.

In a sternly worded letter to the Ontario Pharmacists' Association, Matthews takes issue with reports that pharmacies temporarily withheld services the day the changes were announced.

She also says some industry leaders have been misinforming the public and scaring patients unnecessarily, and adds she's concerned about claims that pharmacies will have to cut back on services like blood pressure checks.

Matthews wouldn't say what action the government might take if pharmacists don't heed her warning, saying only that at this point she is just appealing to their professionalism.

The government says the changes will lower the cost of generic drugs by 50 per cent and clean up abuses when it comes to professional allowances -- payments generic drug companies make to pharmacy owners for stocking their drugs.

Pharmacists warned last week the plan will have a negative impact on the way services are delivered.