The EU has said it "strongly" regrets Donald Trump's surprise plan to double US tariffs on steel and aluminium in a move that risks throwing bilateral trade talks into chaos.

On Friday, the US president told a rally in the steel-making city of Pittsburgh that the tariffs would rise from 25% to 50%, claiming this would boost local industry and national supplies.

The European Commission told the BBC on Saturday that Trump's latest move on tariffs "undermines ongoing efforts" to reach a deal, warning about "countermeasures".

This also raises questions about the UK's zero tariff deal with the US on steel and aluminium which, although agreed, has not yet been signed.

UK steelmakers said the doubling of the tariffs is "yet another body blow" to the industry while a UK government spokesman said "we are engaging with the US on the implications of the latest tariff announcement and to provide clarity for industry".

The UK - which left the EU following the 2016 Brexit referendum - was the first country to clinch a trade deal with the US earlier this month.

Trump tariffs get to stay in place for now. What happens next?

In a statement sent to the BBC on Saturday, the European Commission, the EU's executive arm, said: "We strongly regret the announced increase of US tariffs on steel imports from 25% to 50%.

"This decision adds further uncertainty to the global economy and increases costs for consumers and businesses on both sides of the Atlantic.

"The tariff increase also undermines ongoing efforts to reach a negotiated solution.

"In good faith, the EU paused its countermeasures on 14 April to create space for continued negotiations," the statement said, warning the bloc "is prepared to impose countermeasures".

On Friday, Trump announced the tariff rate on steel and aluminium imports would double to 50%, starting on Wednesday.

He said the move would help boost the local steel industry and national supply, while reducing reliance on China.

Trump also said that $14bn (£10bn) would be invested in the area's steel production through a partnership between US Steel and Japan's Nippon Steel, though he later told reporters he had yet to see or approve the final deal.

The announcement was the latest turn in Trump's rollercoaster approach to tariffs since re-entering office in January.

"There will be no layoffs and no outsourcing whatsoever, and every US steelworker will soon receive a well deserved $5,000 bonus," Trump told the crowd, filled with steelworkers, to raucous applause.

US steel manufacturing has been declining in recent years, and China, India and Japan have pulled ahead as the world's top producers. Roughly a quarter of all steel used in the US is imported.

The announcement comes amid a court battle over the legality of some of Trump's global tariffs, which an appeals court has allowed to continue after the Court of International Trade ordered the administration to halt the taxes.

His tariffs on steel and aluminium were untouched by the lawsuit.

Last week, Trump had agreed to extend a deadline to negotiate tariffs with the EU by more than a month.

In April, he announced a 20% tariff - or import tax - on most EU goods, but later cut this to 10% to allow time for negotiations. Trump expressed frustration with the pace of talks and threatened to raise the tariff rate to an even higher level of 50% as soon as 1 June.

But last week he wrote on social media that he was pushing his deadline back to 9 July, after a "very nice" call with Ursula von der Leyen, the European Commission chief. (BBC)