Economists had already downgraded growth for the European Union, and the new duties would hit industries there especially hard. Companies are looking for ways to blunt the impact.

The European Union is prepared to unleash a €21bn (£18.2bn) retaliation against Donald Trump after the US president announced new tariffs, Italy has said. The euro has fallen and European stocks are on track to open lower after Mr Trump on Saturday said he would impose a 30pc tariff on imports from Mexico and the EU from August 1.

Senior EU officials told the FT that they did not expect Trump to ultimately go through with his new threat of 30 per cent tariffs, which is being widely interpreted by Brussels as a bid by the US President to increase pressure on the bloc in the remaining time left for negotiations.