US President Donald Trump on Thursday authorized the suspension of controversial tariffs on steel and aluminum imports from key trade partners including the European Union.

Trump shocked the world with his sudden announcement earlier this month of a 10-percent levy on aluminum and 25-percent tariff on steel, angering Washington's closest allies, which swiftly demanded that they be exempt.

"The tariffs on steel and aluminum imports from the following countries are suspended until May 1, 2018," the White House said in a statement, listing EU members states, Argentina, Australia, Brazil, Canada, Mexico and South Korea.

"Each of these countries has an important security relationship with the United States," a proclamation from Trump announcing the steel decision said.

The US is in discussions with the countries "on satisfactory alternative means to address the threatened impairment to the national security by imports of steel articles," and tariffs on steel imports from the trade partners will be exempt for now, it said.

US Trade Representative Robert Lighthizer told a Senate committee earlier in the day that the tariff suspension had been authorized by Trump, just hours before the tariffs were to kick in.

"The idea that the president has is that, based on a certain set of criteria, that some countries should get out," Lighthizer said in testimony before the Senate Finance Committee.

Many countries, including those of the EU, warned the White House that they would retaliate forcefully if they were hit with tariffs on metals products.

- 'No use to anyone' -

The climbdown came as Trump announced new sanctions against China for what he called the theft of US intellectual property -- which Beijing has vowed to meet with tit-for-tat retaliation.

China is seen as the root cause of a massive oversupply of steel on the global market, and Europeans in recent days pressed that point with Washington.

EU Trade Commissioner Cecilia Malmstrom made the EU's case over two days this week in Washington, negotiating the carve-out with US Commerce Secretary Wilbur Ross, a strong backer of Trump's "America First" policies.

Arriving at a EU summit, German Chancellor Angela Merkel said "thanks" to Malmstrom "for holding intensive talks with the United States and we will see what the result is."

As a precaution, the commission had drawn up a list of potential counter-measures, including tariffs on peanut butter and Harley Davidson motorcycles, in case Trump followed through.

"We have made it clear that we do not want a trade war. Trade war is of no use to anyone," said Jean-Claude Juncker, chief of the European Commission, which handles trade talks for the 28 member states.

German Economy Minister Peter Altmaier had stressed in Berlin that "fighting until the last minute is worth it," with Germany especially worried about its auto industry.

The close confidant of Merkel reported a "very positive impression" of Ross, whom he also met earlier this week in Washington for last-minute talks.

"We both know what the problem is," Altmaier said, pointing the finger instead at China.