FILE PHOTO: Canada's Prime Minister Justin Trudeau (R) meets with U.S. President Donald Trump during the G7 Summit in the Charlevoix town of La Malbaie, Quebec, Canada, June 8, 2018. REUTERS/Christinne Muschi

OTTAWA (Reuters) - Canada is working with politicians and businesses in the United States to pressure President Donald Trump to scrap tariffs on its steel and aluminum, Prime Minister Justin Trudeau said on Thursday.

Trump imposed the measures last May, citing national security. Canada condemned the move and initially suggested it would not ink a new continental trade pact with the United States and Mexico unless the sanctions were lifted.

Trudeau, who did end up signing the U.S.-Mexico-Canada (USMCA) agreement last November, said the government was trying to change Trump’s mind as the United States prepared to start the ratification of the pact.

“We have already been working with members of Congress, with governors, with business interests who are being affected negatively by these tariffs ... to put pressure on the President that in the process of ratification, they (the United States) should remove those steel and aluminum tariffs,” he said.

Trudeau made his remarks during a televised question-and-answer session with an audience in Regina in the western province of Saskatchewan.

Asked why he had signed the USMCA with the tariffs still in place, Trudeau said securing the deal “at a time of unpredictability and protectionism in the United States was a massive priority for all Canadians”.

Canada sends 75 percent of all its goods exports to the United States.

Trudeau and Trump discussed the tariffs on Monday but no talks on lifting the sanctions are planned, a Canadian source familiar with the matter said.

U.S. Senate Finance Committee Chairman Charles Grassley said on Wednesday the measures would have to be lifted in order to get agricultural interests to support congressional approval for the USMCA.