Donald Trump has said that the agreement allowing the United Kingdom to leave the European Union may make trade between Washington and London more difficult.
The US president also told reporters outside the White House on Monday that the deal sounds like it will be good for the European Union.
“It sounds like a great deal for the EU. I think we have to look seriously at whether the UK is allowed to trade ... if you look at the deal they may not be allowed to trade with us,” he said.
“That wouldn’t be a good thing, I don’t think they meant that. I don’t think the Prime Minister meant that, and hopefully she’ll be able to do something about that.
“Right now, as the deal stands, they might not be able to trade with the US. I don’t think they want that at all. It would be a very big negative for the deal.”
Trump appears to be referring to the section of the deal agreed with Brussels on Sunday that would keep the UK in a customs union if a trade deal with the EU is not agreed during a two-year transition.
The so-called ‘backstop’ - which is to avoid a hard Irish border - would make a UK-US free trade agreement difficult.
In response to Trump’s comments, a Downing Street spokesman said: “The political declaration we have agreed with the EU is very clear we will have an independent trade policy so that the UK can sign trade deals with countries around the world – including with the US.
“We have already been laying the groundwork for an ambitious agreement with the US through our joint working groups, which have met five times so far.
“The US Trade Representative also issued a call for views from the public on a future UK-US free trade agreement earlier this month.”
Trump’s comments echo remarks in July - before the deal with the EU was struck - where the US president warned May’s Brexit plan will “kill” any future US trade deal.
He told The Sun newspaper that Britain remaining so closely aligned to the EU under her plans would undermine a UK-US trade pact - which is seen as one of the biggest prizes after quitting the bloc.
The comments came as it was confirmed that MPs will vote on Mrs May’s Brexit deal on December 11 after five days of debate.
The timing gives May a fortnight to avert what threatens to be a humiliating defeat at the hands of scores of Conservative rebels.
The PM received a largely hostile reception as she told the House of Commons her Brexit deal “delivers for the British people”, and warned that rejecting it would put the UK on the path to division and uncertainty.
She was loudly barracked by MPs as she insisted that no better deal was available than the Withdrawal Agreement and Political Declaration on future relations endorsed by EU leaders in Brussels on Sunday.
Former minister Mark Francois branded her deal a “surrender” and said opposition from Eurosceptic Tories and the Democratic Unionist Party meant it was already “dead as a dodo”.
Ex-defence secretary Sir Michael Fallon described the deal as “a huge gamble” which involved the UK paying a £39 billion divorce bill and giving up its votes and veto without any firm commitment on future trade relations.
But May said: “I believe our national interest is clear.
“The British people want us to get on with a deal that honours the referendum and allows us to come together again as a country, whichever way we voted.
“This is that deal. A deal that delivers for the British people.”
In a sign that she aims to go over fractious MPs’ heads and appeal directly to voters for their backing, Mrs May said parliamentarians had a “duty” to listen to their constituents before taking their decision in the national interest.
But Labour leader Jeremy Corbyn said the Commons would have “very little choice” but to reject May’s “botched” deal, which he described as “bad for this country”.