The prime minister is planning further talks with US President Donald Trump about a looming trade war over steel and aluminium tariffs.
Theresa May’s spokesman said on Monday that the two leaders would discuss the issue again later in the week.
“The prime minister has discussed this with President Trump on a number of occasions already,” he told reporters.
He said Mrs May would again express disappointment at the decision to slap taxes on metals imported by the US.
The Trump administration’s move to put tariffs of 10% on aluminium and 25% on steel from the European Union, Canada and Mexico has been widely condemned.
French President Emmanuel Macron has called Mr Trump to tell him the tariffs were “illegal”, while Canadian Prime Minister Justin Trudeau has said the US move is “totally unacceptable”.
The EU, Mexico and Canada have all set out plans for retaliatory tariffs on US goods.
At the weekend, China – which is not directly impacted by last week’s announcement – warned that all trade talks between Beijing and Washington would be void if the US sets up trade sanctions.
Despite the chorus of criticism, Mr Trump appeared in no mood for compromise. On Saturday, the president tweeted that the US had been “ripped off by other countries for years on trade”.
He says steel tariffs will protect US steelmakers, which he says are vital to national security. Mr Trump has also complained about barriers US firms face in Europe and elsewhere.
“Time to get smart!” he added.
Canada, Mexico and the EU combined exported $23bn worth of steel and aluminium to the US in 2017 – nearly half of the $48bn of total steel and aluminium imports last year.
The EU has responded to the US announcement with a 10-page list of tariffs on US goods ranging from Harley-Davidson motorcycles to bourbon.
Canada plans to impose tariffs of up to 25% on about $13bn worth of US exports from 1 July. Goods affected will include some American steel, as well as consumer products such as yoghurt, whiskey and coffee.