OTTAWA -- With the blessing of the federal government, British Columbia is putting three health clinics under the financial microscope amid long-standing concerns about overbilling and the integrity of the country's public health-care system.

Federal Health Minister Jane Philpott said her department reached an agreement with B.C. to audit the three clinics in hopes of rooting out the practice of extra-billing for medically necessary care, a violation of the Canada Health Act.

"The audit will determine the extent to which extra-billing and user fees have been a barrier to accessible care for people in British Columbia," Philpott said in a statement Thursday.

Philpott's newly appointed B.C. counterpart, former NDP leader Adrian Dix, said he strongly supports the audit agreement, which was negotiated under the province's previous Liberal government.

"We have to act to ensure that access to medical care in B.C. is based on need and not on an individual's ability to pay," Dix said in an interview with The Canadian Press.

"That is the reason the law exists and that is something that has been fundamental to Canada's health-care system for a long time and is something we strongly support."

Health Canada and the province decided to proceed with the audits in March, he said, noting that a considerable amount of planning has flowed from that decision.

"The results of the audit may have consequences ... but the audits haven't been completed yet so commenting on conclusions that haven't been drawn would be incorrect and unfair," he said. "We are not assuming the results of the audits."

The Canada Health Act, which imposes conditions on the provinces and territories in exchange for health care funding, prohibits so-called extra billing or user charges for services that are deemed medically necessary.

Once extra-billing or user charges are confirmed, a dollar-for-dollar deduction from that region's federal health transfer payment is required.

Some $204,145 was deducted from B.C.'s March 2016 transfer payments as a result of extra-billing and user charges for insured health services that were levied at private clinics in the 2013-14 fiscal year.

Extra-billing occurs when a medical practitioner charges an insured patient who receives a covered health service an additional sum over and above what is paid for by a provincial or territorial insurance plan.

Questions about the public health-care system in B.C. have also been raised in a high-profile court case involving Dr. Brian Day of the Cambie Surgery Centre in Vancouver.

In the lawsuit, launched in 2010, Day is challenging B.C.'s ban on the purchase of private insurance for medically necessary services covered by the public system, arguing it forces patients to endure long wait times that can exacerbate their health problems.

The federal government is also engaged in the Cambie case, which it believes could have important implications for public health care across Canada.

Dix said "some of the principles" being defended by the government in the case are similar to the questions at play in the audits.

"It is what the Medical Services Commission in B.C. and the ministry of health are defending in that case," he said.

Philpott, meanwhile, has also warned other provincial counterparts about extra-billing and user fees, noting Ottawa will not tolerate the practice.

She has applauded Quebec for its decision in January to ban user fees, and she has also been in discussions with Saskatchewan officials about upholding the Canada Health Act.

And she has been pushing back against a Saskatchewan law that allows private MRI scans if they are ordered by a doctor and if the private clinic does a second scan to someone on the public wait list at no charge.

Allowing people to pay for private scans contravenes the act, Philpott insists.