The US President Donald Trump says the Brexit agreement "sounds like a great deal" for the EU, but may hinder trade between the UK and US.
Speaking to reporters before a trip to Mississippi, the president said the deal - which was agreed between 27 EU member states on Sunday - may not be good for trade.
"I think we have to take a look at seriously whether or not the UK is allowed to trade because you know right now, if you look at the deal they may not be able 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 (British) prime minister meant that and hopefully she'll be able to do something about that but right now as the deal stands they may not be able to trade with the US and I don't think they want that at all, that would be a very big negative for the deal."
Responding to Mr Trump's comments, a spokeswoman for British Prime Minister Theresa May said that under the existing Brexit agreement the UK will be able to sign trade deals.
She added that the British government had already been "laying the groundwork" for an "ambitious" trade agreement with the US.
Mrs May now faces a fight to get her deal through the House of Commons in the UK.
A vote is set to take place there on December 11th.
UK PM Theresa May speaking following a special meeting of the European Council in Brussels | Image: © European Union
While Mrs May is visiting Northern Ireland on Tuesday as she continues her attempts to sell the agreement.
She will meet students academics and community leaders at an event at Queens University.
She is also due to travel to Wales.
EU leaders, including Taoiseach Leo Varadkar, have insisted this is the only deal available.
Speaking after a special summit in Brussels on Sunday, Mr Varadkar said: "In terms of alternative options and plan B and all of that type of thing, let's not forget what we have here: we have an agreement that took between 18 months and two years to negotiate.
"It, in several parts, is over 500 pages long and, as of today, has the support of 28 governments".
"Anyone can have a better deal or an alternative deal in their own minds - but an agreement 500 pages long that 28 member states can sign up to? Nobody has that - so what's on the table is the only deal that's on the table".
He added the "core difficultly" with people who argue there is a better deal on offer is "they don't agree among themselves what that better deal could be, they probably wouldn't have a majority in parliament for an alternative deal, either - and they certainly wouldn't have 28 member states signed up to it.
"Really what's being put in front of the European Parliament and the House of Commons is a deal - any other deal really only exists in people's imaginations".
