Health Canada says a "range of measures" are in place to combat abuse of its medical cannabis growing regulations, which have recently come under fire from the mayor of Leamington, Ont.

In a statement on Wednesday, the agency also said it is "committed to working with all stakeholders to address issues of concern with its programs."

She has launched a petition seeking reform on licensing and oversight, and wants Ottawa to give provinces and municipalities a role in regulation and enforcement.

"The federal government has failed to subject personal registered medical cannabis production to examination and inspection, allowing grey and black market cannabis operations to flourish under this program," the petition dated May 20 says.

Responding to a request for comment from CBC News, Health Canada said a number of safeguards are in place, including powers to revoke registration for growers on the grounds of public health and safety, inspections of sites, as well as promoting compliance with cannabis regulations.

The vast majority of medical marijuana users access the regular commercially grown product, but about 10 per cent avail of the medical personal use program, according to Health Canada.

It allows people who are prescribed cannabis to grow their own or designate someone else to cultivate it for them, subject to the agency's approval.​

According to Ontario Provincial Police Det.-Insp. Jim Walker, these designations are being exploited by criminals.

He's seen cases where a grower might be licensed to grow 1,200 plants, but has as many as 70,000 to 90,000.

"Not everybody that has personal or designated production registration through Health Canada is abusing it," he said in an interview with CBC News earlier this week.

"There's quite a few that use it for the purposes it was outlined to be, but we have found that organized crime and criminal enterprises are exploiting the loopholes and the lack of accountability on it, to significantly produce large, large quantities of illegal cannabis."

In recent months, the OPP-led Provincial Joint Force Cannabis Enforcement Team has conducted several busts in Leamington and seized more than $100 million in illegally grown pot.

Health Canada 'prepared to act' on cannabis complaints

In its statement, Health Canada said it takes all complaints seriously and is "prepared to act" on any evidence of growers not respecting the conditions of their registration. (The agency has also set up a website where complaints can be lodged against operators.)

From the period between when the Cannabis Act came into force and the end of March, the agency has refused to issue a registration 290 times and has revoked 79 registrations.