TORONTO -- Sun Life Financial Inc. is adding medical marijuana as an option for its group benefits plans, marking an industry shift and the latest sign of growing public acceptance of cannabis.

The Toronto-based insurer's chief executive Dean Connor said the move was influenced by rising interest from Sun Life's employer clients.

"Medical marijuana has become a very important part of their treatment program and pain management program," said Connor, referencing patients who have cancer, multiple sclerosis, rheumatoid arthritis, or those requiring palliative care.

Sun Life provides health benefits coverage to more than three million Canadians and their families, or one in six Canadians.

This new offering comes as the country moves to legalize cannabis for recreational use later this year and as the number of registered medical marijuana patients grows. There were more than 235,000 medical marijuana patients in the system across Canada at the end of September 2017, compared to roughly 98,500 a year earlier, noted Vahan Ajamian, a Beacon Securities Ltd. research analyst.

"The insurance companies have been getting pressure to cover this as a regular medicine," he said.

Starting March 1, plan sponsors with Sun Life will have the option to add medical cannabis coverage to extended health-care plans, ranging from $1,500 to $6,000 per covered person per year.

Medical cannabis coverage will be available for specific conditions and symptoms associated with cancer, rheumatoid arthritis, multiple sclerosis, HIV-AIDS, and palliative care.

In order to qualify for coverage, Sun Life plan members must meet specific criteria including an authorization letter from a physician and registration with a medical marijuana producer licensed with Health Canada.

Sun Life will also conduct periodic reviews of the growing body of clinical research supporting the use of medical cannabis for other conditions, and update its criteria if necessary, the company said in a document updating their client base of 22,300 plan sponsors.

Jonathan Zaid, the executive director of patient advocacy group Canadians for Fair Access to Medical Marijuana, said the enhanced coverage comes after years of litigation to gain this level of acceptance for medical marijuana.

"Although there may not be immediate benefit for patients as specific plan sponsors will need to purchase the coverage, this move will make covering medical cannabis simpler than today's exception process and speaks volumes to the broader acceptance and legitimacy of medical cannabis," he said.

A number of plan sponsors have moved to cover medical cannabis costs over the years, Zaid noted, including the University of Waterloo's student union, the Arthritis Society, Loblaw Companies Ltd., the Ontario Public Service Employees Union (OPSEU), and the Labourers' International Union of North America. Those plans have varying eligibility criteria and levels of coverage, he added.

Manulife Financial Corp., one of Canada's biggest insurers, offers medical cannabis coverage to clients on a selective basis, a spokesperson said.

"Manulife is supportive of clients that want to consider introducing medical cannabis as an option," the spokesperson said in an emailed statement. "We also recommend that clients put limits and some management controls in place as this is an emerging market that is quickly evolving."