The government is taking no chances with security

Heavy security will be put in place to prevent poachers from harvesting the crop, which will be grown 360 metres (1,180 feet) below ground.

The company will be paid some $5.8m ($3.8m US dollars) over five years, and the first harvest is expected a year from now.

Until now, there has been no legal way for people in Canada to obtain marijuana.

Some US states, including Hawaii and Colorado, have also recently begun medical marijuana initiatives.

'Compassion'

"Canada is acting compassionately by allowing the use of marijuana by people who are suffering from grave and debilitating illness," Health Minister Allan Rock said.

"This marijuana will be made available to people participating in structured research programmes, and to authorised Canadians using it for medical purposes who agree to provide information to my department for monitoring and research purposes."

It is illegal to possess marijuana in Canada, but a 1999 law has allowed some people who consume marijuana medicinally to escape criminal prosecution.

So far, some 140 Canadians have earned exemptions under the law, but providing them with their regulated supply has been difficult.

Prairie Plant Systems will get the pot seeds from research authorities in other countries with similar medical marijuana programmes.