WASHINGTON (AFP, NYTIMES) - US President Donald Trump on Thursday (March 23) authorised the suspension of controversial tariffs on steel and aluminum imports from key trade partners including the European Union.

But in a twist, the administration might impose import quotas to prevent too much foreign metal from flooding into the United States.

"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 had told a Senate committee earlier in the day that the tariff suspension had been authorised by Trump.

"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.

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Trump signed the tariffs - 25 per cent on imported steel and 10 per cent on imported aluminum - earlier this month, drawing condemnation from allies and sparking fears of a trade war.

Many countries, including the EU, warned the White House that they would retaliate forcefully if they are faced with tariffs on metals products.

The Trump administration has stressed that the primary target is China, which has long had massive overproduction that has impacted the global market for steel and aluminum.

The exemptions would provide a reprieve to top trading partners, but a person familiar with the administration's thinking cautioned that the United States is likely to impose quotas on the overall level of metals sent into the United States.

Peter Navarro, a top trade adviser to Trump, confirmed in a television appearance on Thursday that the White House would impose quotas.

"Every country that is not facing tariffs that we're going to negotiate with will face quotas so that we protect our aluminum and steel industries. For all countries, there has to be a quota," Navarro said on CNN.

"If you don't put a quota on, then any country that can do whatever they want will become a transshipment point for every other country."