US media reported the president asked lawmakers why "people from shithole countries" were arriving in the US
A United Nations spokesperson has described remarks by Donald Trump during a meeting about immigration as 'shocking and shameful'.
President Trump himself has suggested the reported foul-mouthed outburst was 'not the language used'.
According to multiple US media outlets, he made the comments during a meeting with lawmakers.
The Washington Post reported that the bipartisan group was meeting as part of efforts to reach a deal on immigration, including for people from Haiti, El Salvador and African countries.
The US president is reported to have said: "Why are we having all these people from shithole countries come here?".
Singling out Haiti, he allegedly added: "Why do we need more Haitians? Take them out."
He then apparently suggested the US should bring in more people from countries such as Norway.
The US president has denied using the expletive - however, Democratic senator Dick Durbin was in the meeting:
In an initial statement provided to media, White House spokesperson Raj Shah did not deny the comments, instead arguing: "Certain Washington politicians choose to fight for foreign countries, but President Trump will always fight for the American people.
"He will always reject temporary, weak and dangerous stopgap measures that threaten the lives of hardworking Americans, and undercut immigrants who seek a better life in the United States through a legal pathway."
This afternoon, President Trump insisted "never said anything derogatory" about the Haitian people - and claimed the accusations were "made up" by Democrat politicians:
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
That followed a series of tweets on Friday morning, in which he began by warning that little progress had been made at the bipartisan meeting - saying efforts to find a solution have "now taken a big step backwards."
Then, appearing to refer to the reported comments, he added: "The language used by me at the DACA meeting was tough, but this was not the language used."
The language used by me at the DACA meeting was tough, but this was not the language used. What was really tough was the outlandish proposal made - a big setback for DACA!— Donald J. Trump (@realDonaldTrump) January 12, 2018
Both major US political parties have been trying to reach an agreement on an immigration scheme - called Deferred Action for Childhood Arrivals (DACA) - which was introduced by the Obama administration in 2012.
It protects around 800,000 people who entered the US illegally as children - also known as 'Dreamers' - from deportation for a renewable two-year period, while allowing them to work.
Trump has been calling for funding for his proposed Mexican border wall in return for protecting the DACA scheme.
The reported remarks have been condemned both by US and international officials.
UN human rights spokesperson Rupert Colville said: "If confirmed, these are shocking and shameful comments from the President of the United States. Sorry, but there is no other word one can use but 'racist.'
"You cannot dismiss entire countries and continents as 'shitholes' whose entire populations, who are not white, are therefore not welcome.
"The positive comment on Norway makes the underlying sentiment very clear.
"Like the earlier comments made vilifying Mexicans and Muslims, the policy proposals targetting entire groups on grounds of nationality or religion, and the reluctance to clearly condemn the anti-semitic and racist actions of the white supremacists in Charlottesville - all of these go against the universal values the world has been striving so hard to establish since World War II and the Holocaust.
"This is not just a story about vulgar language, it's about opening the door wider to humanity's worst side, about validating and encouraging racism and xenophobia that will potentially disrupt and destroy the lives of many people.
"That is perhaps the single most damaging and dangerous consequence of this type of comment by a major political figure."
The comments provoked immediate criticism in the US, from both Republicans and Democrats.
Utah representative Mia Love, who is Haitian-American and a Republican, hit out at the 'unkind, divisive and elitist' comments.
Here is my statement on the President’s comments today: pic.twitter.com/EdtsFjc2zL— Rep. Mia Love (@RepMiaLove) January 11, 2018
Democratic Congressman Luis Gutierrez said in a statement: "As an American, I am ashamed of the President. His comments are disappointing, unbelievable, but not surprising.
"We always knew that President Trump doesn’t like people from certain countries or people or certain colors. We can now we say with 100% confidence that the President is a racist who does not share the values enshrined in our Constitution or Declaration of Independence."
CNN anchor Anderson Cooper, meanwhile, got emotional on air while recalling his own experiences in Haiti:
"Let me be clear.... the people of Haiti have been through more, withstood more, fought back against more injustice... than our President ever has" Anderson Cooper choked back tears as he reflected on his relationship with Haiti, and its people https://t.co/3arEalkKOM— Anderson Cooper 360° (@AC360) January 12, 2018
Meanwhile, former FBI director James Comey - who was fired by President Trump last year - quoted the message on the Statue of Liberty, and suggested "this country's greatness and true genius lies in its diversity".
“Give me your tired, your poor, your huddled masses yearning to breathe free, the wretched refuse of your teeming shore. Send these, the homeless, tempest-tossed to me, I lift my lamp beside the golden door!” This country’s greatness and true genius lies in its diversity.— James Comey (@Comey) January 12, 2018
Additional reporting: Jack Quann