What's believed to be a booming business in illegal cigarette sales in Saskatchewan is a growing health concern, the Canadian Cancer Society says.

In particular, the availability of cheap cigarettes at First Nations stores is something that needs to be more closely monitored, officials with the organization said Tuesday in Regina

The provincial government gives tobacco tax rebates to First Nations stores, if the stores show their cigarettes were sold to tax exempt Indians.

According to Saskatchewan Finance Ministry figures, rebates have jumped from $3 million in 2000 to an estimated $50 million last year.

But given that there has been no significant increase in the First Nations population over those years, many cigarettes must be ending up on the black market for sale to non-First Nations people, the society says.

"Quantities of cartons are being acquired by non-natives, and put in car trunks and being sold, illegally, off-reserve," said Rob Cunningham, the cancer society's senior policy analyst. "That is an indication that things are out of control."

The society sees high tobacco taxes as the most important way to  discourage people from smoking. But tax-rebatable cigarettes on reserves tend to be half the cost of cigarettes sold to non-First Nations people, it says.

Provincial officials say they monitor cigarette sales at First Nations stores and while there may be some cheaters, there are also explanations for the rise in tax rebates.

"Exempt sales have been going up on reserve but partly that's because of … more on-reserve stores, so more individuals [are] able to buy tax-free," Finance Ministry spokesman Doug Lambert said.

Over the past decade, the number of First Nation stores has gone from less than 30 to more than 100, Lambert said.

The cancer society says it would like to see tougher quotas on how many cigarettes First Nations people can buy to discourage contraband sales to the rest of the province.