Saskatchewan's justice minister says the provincial government has some "real concerns" about new legislation to be introduced today in Ottawa to legalize marijuana.

"We don't really have a way of monitoring or at least of detecting people who are driving on the roads who may be impaired by marijuana," said Gord Wyant.

"There's people that are out there operating heavy machinery and we need to make sure that our workplaces are safe."

Wyant says the consumption of alcohol is a "bit more obvious" than that of pot, which may make it hard to detect the latter in the workplace.

"You can smell alcohol on someone's breath," Wyant said.

He said the province's construction association has already expressed its concerns to government about the issue.

Wyant said he has written to the federal government to find out who will bear the cost of extra training for police officers to detect impairment due to marijuana in drivers.

In the letter, Wyant also urges his federal counterpart to increase the minimum age for cannabis use to 19 from 18 across the country.

The legal drinking age in Saskatchewan is 19 and Wyant says to create a different age for cannabis, "especially in the context that our medical experts tell us young adult brains continue to develop until at least age 25, would be counterproductive."

Marijuana is expected to be legal by Canada Day next year.