TORONTO - A B.C. producer of medical marijuana has voluntarily recalled a batch of its "purple kush" strain and is advising consumers not to smoke the weed after a Health Canada inspection of the grower's operations turned up "issues" with its production practices.

In what is believed to be the first recall of medical cannabis in Canada, Greenleaf Medicinals of Nanaimo, B.C., is advising clients to immediately stop using any marijuana they still possess from batch number PK-10-20-13.

"Following an inspection at Greenleaf Medicinals, Health Canada inspectors identified issues with processes that affect quality control, good production practices and oversight," a spokesman for the federal department said late Tuesday by email.

"This includes potential residues from use of unregistered pesticides, unsanitary production conditions, concerns with testing standards and/or control of plant materials."

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Health Canada did not say what adverse effects might occur from smoking or ingesting the recalled pot.

Greenleaf could not be reached for comment; its website appears to have been taken down and the company's name does not appear on Health Canada's online list of authorized growers of medical marijuana.

The Health Canada spokesman said Greenleaf has been temporarily removed from the list until its production problems have been corrected and its operations re-inspected.

The company has told Health Canada it is working with other licensed producers to find a supply of marijuana for 63 clients affected by the recall of its purple kush, a potent strain of cannabis that contains a high concentration of the psychoactive ingredient THC.

Greenleaf has advised customers to return the product to the company via a secure courier.

If clients instead choose to destroy the product, they should add water to the dried marijuana to render it unusable, mix it with cat litter to mask the odour and dispose of it with regular household waste.