Prairie Plant Systems, which has grown medical marijuana under contract with the federal government since 2000 has been forced to move its operation out of a Flin Flon mineshaft. (CBC)

Medical marijuana is no longer being grown in an old mine shaft in northern Manitoba.

The project's Saskatoon-based owner ceased operations at the Hudson Bay Mining and Smelting facility in Flin Flon on June 30.

Prairie Plant Systems has had a contract with Health Canada since late 2000 to grow the medical marijuana. But company president Brent Zettl said he couldn't secure long-term access to the mine because HBMS is closing it down in 2012.

Prairie Plant Systems had planned to expand its grow operation in the mine, but Zettl said that will have to wait.

About 300 Canadians annually receive marijuana grown by Prairie Plant Systems. (CBC)

"We haven't formally made an announcement, but certainly [moving out] seems to be the only option at this time," Zettl said. He's holding a meeting next week before a final decision about the expansion.

Jobs for about 18 people from Manitoba and Saskatchewan have been lost as a result of the marijuana operation shutting down.

Zettl has not identified other possible locations for the production of the plants. Health Canada could not be reached for comment about the impact of the Prairie Plant Systems shutdown on supplies.

Ottawa has been a reluctant supplier of pot since a series of court rulings forced it into the medical marijuana business. The government's marijuana program licenses certified medical users to grow their own pot, to have someone grow it for them or to buy it straight from Health Canada.

More than 1,400 Canadians are authorized to possess marijuana for medical purposes. Of those, about 300 people receive the Prairie Plant Systems product. Patients must have the support of their doctors to be considered for authorization.