BRUSSELS - The European Union (EU) on Tuesday said the US decision to extend the bloc's exemption from import tariffs on steel and aluminium has prolonged market uncertainly and has impacted business decisions.

"The EU should be fully and permanently exempted from these measures, as they cannot be justified on the grounds of national security," the European Commission said in a statement.

The White House on Monday announced that the steel and aluminum tariff exemptions for EU member countries, Canada and Mexico will be extended until June 1 in order to give "a final 30 days" for them to reach agreements over trade negotiations.

The EU said it had "consistently indicated its willingness to discuss current market access issues of interest to both sides," and also made it clear that the EU will "not negotiate under threat."

"Any future transatlantic work program has to be balanced and mutually beneficial," the statement said.

European Commissioner for Trade Cecilia Malmstrom has been in contact with US Commerce Secretary Wilbur Ross and US Trade Representative Robert Lighthizer over the past few weeks, and these discussions will continue, it added.

Amid widespread dissent from business groups and trading partners around the world, Trump signed proclamations in March to impose a 25-percent tariff on imported steel and 10 percent on aluminum, which took effect on March 23.

The White House then provided temporary exemptions for EU member states as well as Argentina, Australia, Brazil, Canada, Mexico and South Korea, and had to decide whether to extend them until the end of Monday.

The United States is using a decades-old law to impose the tariffs on national security grounds, which has drawn strong opposition from the domestic business community and US trading partners.

Last week, French President Emmanuel Macron and German Chancellor Angela Merkel went to Washington to work out trans-Atlantic trade issues but left empty handed.

China has requested consultations with the United States about the tariffs at the World Trade Organization, something the EU has sought to join.

Though the EU is temporarily exempt from the tariffs, if the exemption is not continued, its exports would be impaired significantly, it said last week.