THERESA May has clashed with Donald Trump again, this time over his threat to slap huge tariffs on imported steel.

The Prime Minister – who is seeking to strike a trade agreement with the US post-Brexit – made clear her concern about the President’s trade war threat in a phone call yesterday afternoon.

READ MORE: We need to secure independence before the global trade wars begin

She said “multilateral action” was the only way to tackle the problem of global over-supply of steel.

Trump last week announced that steel imports into the US would face a 25 per cent tariff and aluminium a 10 per cent tariff. He said he was taking the action to protect the American steel industry, which he argued had been “decimated” by global trade policies.

Setting out his position on Twitter, the president said trade wars were “good”.

He posted: “When a country (USA) is losing many billions of dollars on trade with virtually every country it does business with, trade wars are good, and easy to win. Example, when we are down $100 billion with a certain country and they get cute, don’t trade anymore – we win big. It’s easy!”

He continued to set out his views on Saturday by threatening to impose taxes on cars imported to America from the EU.

“The United States has an $800 Billion Dollar Yearly Trade Deficit because of our “very stupid” trade deals and policies. Our jobs and wealth are being given to other countries that have taken advantage of us for years. They laugh at what fools our leaders have been. No more!” he wrote.

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

Following May’s call to Trump yesterday, a Downing Street spokesman 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.”

The two leaders also discussed the ongoing civil war in Syria, in particular “the appalling humanitarian situation in Eastern Ghouta”, the spokesman said.

“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,” the spokesman added.

“They agreed that Russia and others with influence over the Syrian regime must act now to cease their campaign of violence and to protect civilians.”

The row over steel tariffs is the latest in a long line of clashes between May and Trump.

Last month, the Prime Minister hit back after the US President claimed the NHS was “broke and not working”.

The incident followed a rebuke from May in November, when she said President Trump was “wrong” to retweet anti-Muslim posts from far-right group Britain First.

The pair have also clashed on other issues, including Trump’s decision to ban immigrants from some Muslim countries and the US’s withdrawal from the Paris climate change agreement.