Canada's Foreign Minister Chrystia Freeland, showing off her waggish side, wore a t-shirt with the words "Keep calm and negotiate NAFTA" on it to Washington for high level continental trade talks Wednesday.

The minister was spotted at the Ottawa airport late Tuesday sporting the white shirt as she walked to the gate to catch her flight. A photo was posted on Twitter.

Her spokesman Adam Austen told AFP "it was a gift from her children! She wears it all the time."

The related "Keep Calm and Carry On" slogan dates back to 1939, when the British government put it on motivational posters in preparation for World War II to reassure the public in the face of predicted mass air attacks on major cities.

It has resurfaced in the last decade on t-shirts and other paraphernalia. Canadian media have touted Freeland's attire as a sign that Ottawa is not prepared to cave to US negotiating pressures.

Prime Minister Justin Trudeau in a telephone call with US President Donald Trump on Tuesday "reaffirmed his commitment to a deal that works for both countries," according to a readout of the call.

Freeland was scheduled to meet with US Trade Representative Robert Lighthizer at 11 a.m. (1500 GMT) to try to hammer out a deal to revamp the North American Free Trade Agreement, which she said last week after a round of tense talks was "eminently possible."

For the meeting, however, she changed into a more formal black dress accented with a pearl necklace.

Ottawa in no rush for deal

Negotiations to modernize the 1994 accord between Canada, the United States and Mexico started a year ago at the behest of president Trump, who called it "one of the worst trade deals in history" for sending many manufacturing jobs

notably in the auto sector - to Mexico

The United States and Mexico sealed their own two-way deal at the end of August, and Trump has since ramped up pressure on Canada to accept his terms.

But Ottawa has seemed reluctant to heed Trump's push to sign a deal before US midterm elections in November and the transfer of power in December to Mexican President-elect Andres Manuel Lopez Obrador -- as Trudeau's Liberals also need a win to hold up to voters when they return to the polls in one year.

Stumbling blocks to a deal remain, including over Canada's protected dairy sector and cultural subsidies, as well as its demand for an international system for resolving disputes. (AFP)