HOW AMERICA RAISED THE STAKES

Donald Trump announced in March that the EU and countries including Mexico, Canada and Brazil would be hit by increased steel and aluminium tariffs to protect US firms against imports from China, which has flooded the market with cut-price steel.

The EU, which negotiates trade on behalf of Britain, was granted a temporary exemption while Theresa May and other leaders lobbied for a permanent reprieve.

The UK is concerned about the effect of the measures on its resurgent £1.6billion steel industry, which employs 31,000.

Britain exported 350,000 tonnes of steel worth £376million to the US last year – 7 per cent of its output.

If the EU hits back, as it has threatened to do, Britain fears that Mr Trump will retaliate by raising tariffs on cars, in a blow to the UK car industry, which employs 169,000.