Theresa May has expressed the UK’s “deep concern” at Donald Trump’s decision to raise tariffs on steel and aluminium.

The Prime Minister raised the issue during a call with the US President on Sunday afternoon.

Mr Trump has outlined plans to impose a 25 per cent tariff on steel imports and 10 per cent on aluminium.

A Downing Street spokesperson said: “The Prime Minister raised our deep concern at the President’s forthcoming announcement on steel and aluminium tariffs, noting that multilateral action was the only way to resolve the problem of global overcapacity in all parties’ interests.”

It comes after Ms May’s de facto deputy, David Lidington, warned Mr Trump it was a mistake to hike tariffs and start a trade war with the EU.

He told the BBC’s Sunday Politics: “I just think that the United States is not taking an advisable course in threatening a trade war.

“Trade wars don’t do anybody any good.”

The EU has responded to Mr Trump’s threats by imposing its own trade penalties in the US. That prompted the US President to make further threats, this time to impose a new tax on cars manufactured in Europe.

He wrote on Twitter: “If the EU wants to further increase their already massive tariffs and barriers on US companies doing business there, we will simply apply a Tax on their Cars which freely pour into the US. They make it impossible for our cars (and more) to sell there. Big trade imbalance!” 

Ms May and Mr Trump also discussed the situation in Syria. 

The Downing Street spokesperson said: “They discussed Syria, and the appalling humanitarian situation in Eastern Ghouta. They agreed it was a humanitarian catastrophe, and that the overwhelming responsibility for the heart-breaking human suffering lay with the Syrian regime and Russia, as the regime’s main backer.