WASHINGTON (Reuters) - U.S. President Donald Trump's planned 25% tariffs on all steel and aluminum imports would be added onto other levies on Canadian goods, resulting in a total 50% tariff, a White House official said on Tuesday.

Canada has not been told about the stacking of the tariffs, a government source told Reuters, adding that it "sounds plausible."

Earlier this month, Trump imposed 25% tariffs on most Canadian imports. However, those the tariffs were paused for 30 days last week.

On Monday, Trump signed proclamations raising the U.S. tariff rate on aluminum to 25% from his previous 10% rate and eliminating country exceptions and quota deals as well as hundreds of thousands of product-specific tariff exclusions for both metals.

The measure, which would take effect on March 12, was met with opposition by Canada with Canadian Prime Minister Justin Trudeau calling it "unacceptable".

The Canadian Press, citing a senior government official, reported that Trudeau spoke with U.S. Vice President JD Vance about the impact the steel tariffs would have in Ohio, which Vance previous represented in the U.S. Senate.

(Reporting by Jarrett Renshaw and Jasper Ward; Additional reporting by David Ljuggren in Ottawa; editing by Costas Pitas)