The Ontario government will start cracking down on doctors who tack on extra fees to services covered by OHIP.

The effort is aimed at health providers who often charge accessory fees for routine procedures, like a "nutrition counselling fee" that accompanies a colonoscopy.

Health Minister Deb Matthews said that is illegal, and it's not the only shady practice to hit customers in the wallet.

"When people go in for cataract surgery, they are told they can only have it done by that provider if they spend an additional amount of money to buy an upgraded lens," she said.

The government said Tuesday it would expand its investigations and spot checks into clinics that are named in repeated complaints.

It's launching a toll-free number to call for those who have complaints. But it is not investing any extra money in the crackdown.

"I'm very pleased to see the government taking this step," said Dr. Danielle Martin, who leads the group Canadian Doctors for Medicare.

She said the government's move targets something called linking, when a clinic says patients can only receive a treatment covered by OHIP if they pay for another service that is not insured.

"It clarifies that that is in fact, illegal and that if clinics want to charge patients for uninsured services, it has to be made clear to the patient that the charge is optional and the service is optional and you can still just go to the clinic and get your OHIP coverage service and go home without ever having to ever take out your credit card," she said.

"It's really, really important that people come forward ... so that the government can look into those clinics and clarify their obligations to adhere to the law."

The Health Ministry has recovered a little more than $1 million in illegal medical fees over the past four years.

Those who have complaints about illegal billing can call 1-888-662-6613 or email protectpublichealthcare@ontario.ca.