PROPOSED increases to metal tariffs by US President Donald Trump would be “devastating” for the British steel industry, Unite warned today.

Setting out plans for a 15 per cent tariff on steel imports and 10 per cent on aluminium, Mr Trump said US domestic industry had been “decimated” by “unfair” trade policies and would not be “taken advantage of any longer.”

Unite’s national officer for steel Tony Brady warned however that the measure would add to pressures on British steel, which had already been taken “to the precipice” by government inaction against cheap Chinese steel dumping.

Demanding that Prime Minister Theresa May support steelworkers, Mr Brady said: “US tariffs on British steel would be devastating for the industry and the thousands of workers who have battled for its survival alongside their trade unions.

“Any tariffs imposed on British steel by President Trump on the scale that is being mooted would be misguided and deprive US manufacturers of some of the most specialist steel in the world.

“Government ministers and Theresa May must back Britain's steelworkers and manufacturing communities by securing assurances from President Trump that they will not be caught up in a global tariff war between the US and countries such as China.”

UK Steel head of policy Richard Warren said the US was a significant export market for British producers and that Mr Trump’s proposed tariffs would have “a significant impact.”

He said that, “considering the thin margins that larger steel operators will be operating to, 25 per cent is a significant tariff.”

Canada and the EU both indicated they would retaliate to any tariffs, potentially starting a trade war with the US.

European Commission president Jean-Claude Juncker said the EU would “react firmly and commensurately to defend our interests,” while Canadian Foreign Minister Chrystia Freeland said Canada would take “responsive measures” if restrictions were imposed.

A Downing Street spokesman said the government was “particularly concerned” about any measures that would impact Britain steel or aluminium, but said it was not yet clear if Britain would be included in any tariffs.

They added that the government was “engaging with the US on what this announcement means in practice.”