Former secretary of state Hillary Rodham Clinton has urged Canada to forge a unified front with its U.S. neighbour to counter what she portrayed as heightened aggression by Russia in the Arctic.

Speaking to a sold-out crowd in Montreal on Tuesday night, the former first lady and possible future presidential candidate used her podium to denounce Russian President Vladimir Putin's actions not just in Ukraine, but closer to Canada's borders.

Russia has the longest coastline in the Arctic, and "they have been aggressively reopening military bases" in the region, she told an audience in a talk hosted by the Board of Trade of Metropolitan Montreal. The country recently imprisoned several Greenpeace activists and regularly sends military air flights over parts of Canada and Alaska, "testing our responses."

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"We need a united front," she said, adding that the opening of Arctic exploitation and Canada's "huge coastline" is pressing the issue.

Ms. Clinton spent most of her talk to more than 4,000 ticket holders focusing on her favoured theme of empowering women around the world through increased participation work and public life. As a testament to her high-wattage star power despite losing the Democratic nomination to Barack Obama in 2008, her speech attracted members of Quebec's business and political elite.

All three main provincial party leaders, including Premier Pauline Marois, were in the audience, along with the mayors of Montreal and Quebec City and federal cabinet ministers John Baird and Denis Lebel.

Ms. Clinton lived up to the reputation she earned as her country's top diplomat by scrupulously avoiding the treacherous terrain of Quebec politics – omitting any word about the province and zeroing in on Canada's strong relationship with the United States.

Earlier in the day, Premier Marois praised Ms. Clinton's "resilience" and her "capacity to serve her country."

Ms. Marois might have been disappointed if she'd hoped for a boost from Ms. Clinton, who has been dubbed the most powerful woman in U.S. history. Ms. Clinton said she is "a great fan of Canada."

Ms. Clinton hammered Mr. Putin's moves into Crimea, saying he acted in violation of international law.

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"This is a clash of values. It's an effort by Putin to rewrite the boundaries of post-World War II Europe," she said, predicting similar treatment for other countries if Russia is allowed to "get away with it."

"There's a lot at stake here."

Ms. Clinton is considered a frontrunner as the Democratic presidential candidate in 2016, but nimbly sidestepped the question of whether she would run.

"I haven't made up my mind," she said.