Donald Trump has suggested Theresa May's Brexit agreement could threaten a US-UK trade deal.
The US president told reporters the withdrawal agreement "sounds like a great deal for the EU" and meant the UK might not be able to trade with the US.
No 10 insisted it is "very clear" the UK would be able to sign trade deals with countries around the world.
Downing Street added that Mrs May is ready to defend her deal in a TV debate with Labour leader Jeremy Corbyn.
It has been reported the debate could take place on 9 December - two days before the Parliamentary vote on Mrs May's deal.
Speaking to reporters outside the White House, Mr Trump said: "Right now if you look at the deal, [the UK] may not be able to trade with us. And that wouldn't be a good thing. I don't think they meant that."
It would appear Mr Trump was suggesting the agreement could leave Britain unable to negotiate a free-trade agreement with the United States.
Cabinet Office minister David Lidington said Mr Trump's comments "were not unexpected" and negotiations on a trade deal with the US were always going to be "challenging".
"The United States is a tough negotiator," he told BBC Radio 4's Today. "President Trump's always said very plainly 'I put America first'. Well, I'd expect the British prime minister to put British interests first."
The comments came after Mrs May fought off criticism of her Brexit deal from MPs on all sides of the Commons on Monday - insisting the agreement would allow the UK to regain control of laws, money and borders.
Source: bbc