WASHINGTON (Reuters) -U.S. President Donald Trump on Monday said he would announce plans to impose reciprocal tariffs on other countries over the next two days, doubling down on comments he made on Sunday.

The Republican president spoke to reporters in the Oval Office as he signed two proclamations ending all exclusions on steel and aluminum tariffs first imposed during his first term and raising duties on both metals to 25%. Trump said he was also looking at tariffs on cars, semiconductor chips and pharmaceuticals.

A U.S. official said the exclusion process begun under Trump had gotten out of control under former President Joe Biden, resulting in approval of hundreds of thousands of specific product exclusions.

Asked about the possibility of other countries retaliating against U.S. tariffs, Trump said: "I don't mind."

In an interview with Fox News, Trump said other countries had imposed duties on imports from the United States for years.

"It's not fair that other countries have taken advantage of us for so many years, and now all of a sudden, we're not allowed to have tariffs," he said.

Trump told Fox News in the interview that he would announce a "very sophisticated plan" for the reciprocal tariffs, probably Monday or Tuesday.

(Reporting by Steve Holland; writing by Andrea Shalal; Editing by Leslie Adler and Lincoln Feast.)