Donald Trump's reported remark branding Haiti, El Salvador and unspecified African nations as "s***hole countries" has been branded racist by a UN human rights official.
"If confirmed these are shocking and shameful comments from the President of the United States," spokesperson Rupert Coleville said.
"There is no other word you can use but 'racist'."
"You cannot dismiss entire countries and continents as 's***holes', whose entire populations who are not white, are therefore not welcome."
The US President made the comment during a meeting with congressional leaders in the Oval Office on Thursday, according to US media.
“Why are we having all these people from s***hole countries come here?” Mr Trump said after being presented with a proposal to restore protections for immigrants from the countries in question.
He asked to know why the US would not instead accept people from places like Norway, whose prime minister he had met with the day before.
The White House defended Mr Trump's policies on immigration and failed to deny he had made such comments.
Mr Coleville added: "This isn't just a story about vulgar language, it's about opening the door to humanity's worst side, about validating and encouraging racism and xenophobia."
Mr Trump eventually issued a denial on Twitter, saying the language he used was "tough" but different to what was claimed.
"Never said anything derogatory about Haitians other than Haiti is, obviously, a very poor and troubled country," he continued.
"Never said 'take them out'. Made up by Dems. I have a wonderful relationship with Haitians. Probably should record future meetings - unfortunately, no trust!"
Never said anything derogatory about Haitians other than Haiti is, obviously, a very poor and troubled country. Never said “take them out.” Made up by Dems. I have a wonderful relationship with Haitians. Probably should record future meetings - unfortunately, no trust!— Donald J. Trump (@realDonaldTrump) January 12, 2018
The African Union (AU), a group representing all 55 countries on the continent, said it was "frankly alarmed" by the US President's alleged comments.
"Given the historical reality of how many Africans arrived in the United States as slaves, this statement flies in the face of all accepted behaviour and practice," AU spokeswoman Ebba Kalondo said.
"This is particularly surprising as the United States of America remains a global example of how migration gave birth to a nation built on strong values of diversity and opportunity."
Robert Reich, former Secretary of Labor under President Bill Clinton, compared Mr Trump's comments to Nazism.
"To the Nazi's, the purest Aryans were the Nordic people of Germany and Norway," he wrote on Twitter, alluding to Mr Trump's complaint that more Norwegians were not allowed into the US.
"Connection?" he added.
To the Nazi's, the purest Aryans were the Nordic people of Germany and Norway. “Why are we having all these people from shithole countries [Haiti and Africa] come here?” Trump exploded today, saying the U.S. should bring more people from countries like Norway. Connection?— Robert Reich (@RBReich) January 11, 2018
Mr Trump made immigration reform a central theme of his campaign and on Thursday was meeting with members of Congress in an attempt to thrash out a deal.
Since taking office, he has announced he will end Temporary Protected Status (TPS) for several groups in the US, including Haitians and Salvadorans.
TPS is an immigration status for certain countries experiencing crises such as natural disasters or war.
Haitians became eligible for TPS following a 2010 earthquake that devastated the Caribbean island nation, and from which it is yet to recover. The White House said it will end the designation for Haiti by July 2019.
On 8 January the Department of Homeland Security announced it was ending TPS status for around 200,000 Salvadorans. The privilege was given to El Salvador following a series of earthquakes in 2001.