European Commission chief Ursula von der Leyen hit out Saturday at new tariffs threatened by US President Donald Trump, and said the EU still sought a deal with Washington to avert the measures. 

"Imposing 30 percent tariffs on EU exports would disrupt essential transatlantic supply chains, to the detriment of businesses, consumers and patients on both sides of the Atlantic," von der Leyen said in a statement. 

"We remain ready to continue working towards an agreement by August 1. At the same time, we will take all necessary steps to safeguard EU interests, including the adoption of proportionate countermeasures if required," she added.

Von der Leyen insisted that "few economies in the world match the European Union's level of openness and adherence to fair trading practices."

"The EU has consistently prioritized a negotiated solution with the U.S., reflecting our commitment to dialogue, stability, and a constructive transatlantic partnership," she said. 

Trump on Saturday said major US trading partners the European Union and Mexico would face a 30 percent tariff starting next month, ramping up pressure for deals in his trade wars. 

Both sets of duties would take effect August 1, Trump said in separate letters posted to his Truth Social platform, citing Mexico's role in illicit drugs flowing into the United States and a trade imbalance with the EU respectively.

An EU spokeswoman said that Brussels had been informed of the new tariffs before Trump published the letters online. 

The EU tariff is also markedly steeper than the 20 percent levy Trump unveiled in April, as negotiations with the bloc continue.

The EU, alongside dozens of other economies, had been set to see its US tariff level increase from a baseline of 10 percent on Wednesday, but Trump pushed back the deadline to August 1 just days before the elevated rates were due to take effect.

The EU has prepared retaliatory duties on US goods worth around 21 billion euros after Trump also slapped separate tariffs on steel and aluminum imports earlier this year, and they are suspended until July 14.

European officials have not made any move to extend the suspension but could do it quickly if needed.

Diplomats said that an unscheduled meeting of ambassadors from the EU's 27 countries has been convened in Brussels for Sunday afternoon to discuss the latest move from Trump.