Minimum ages for marijuana consumption may vary across Canada when it becomes legal, but authorities will be firmly against drug tourism and cross-border movement of the substance, the Liberal government's point man on the issue said on Wednesday.

The government also wants consistent nation-wide impaired-driving laws for marijuana, said Bill Blair, parliamentary secretary to the justice minister, as the country formulates a new drug law ahead of a spring 2017 deadline.

"We would like to see consistency and a consensus across the country on the best way to keep our roadways safe," Blair, the former Toronto police chief, said at an interview in his Toronto constituency office.

He said provinces should have a say, but legalization led by individual regions, such as in the United States, causes a "difficult situation," in which state laws sometimes contradict federal laws.

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Canada's Liberal government said in April it will introduce legislation to legalize marijuana's recreational use. It has formed a task force that will report back in November.

Blair cautioned the government has not made firm decisions on many aspects of legalization, which will be heavily influenced by the task force's report. But he said the government does "not necessarily" need a nation-wide marijuana consumption age, citing different ages provinces have for alcohol use.

Canada intends to implement regulations to "discourage" drug tourism, as the country is taking a strict public-health approach and is not out to make money, he said.

Blair said people will not be able to take marijuana out of the country due to international conventions restricting drug movement. The government may also increase penalties for trafficking, which would remain an issue as foreign marijuana would not have adequate quality controls, he said.

He and other politicians have said that for now, unregulated marijuana sales remain illegal, despite their flourishing since the Liberals came to power.

But enforcement, handled by municipalities, has been inconsistent, and many marijuana shops continue to openly defy the law.

Blair said enforcement is ultimately not a federal matter, though he is satisfied with the current level of enforcement.

"It doesn't mean everybody needs to be in jail," he said.