Trump 'in crude Oval Office outburst about migrants'
"Why are we having all these people from shithole countries come here?" Mr Trump reportedly asked lawmakers during talks on an immigration deal.
He was apparently referring to Haiti, El Salvador and African countries.
The White House made no attempt to deny the comment.
In recent weeks, the Trump administration has been trying to limit the number of family members of immigrants who can enter the US, and has moved to end the protected status of thousands of immigrants already in the US.
What did the president say?
Mr Trump's reported remark came as lawmakers from both parties visited him on Thursday to propose a bipartisan immigration deal.
Democratic Senator Richard Durbin had just been discussing US temporary residency permits granted to citizens of countries hit by natural disasters, war or epidemics, according to US media.
According to the Washington Post, Mr Trump told lawmakers the US should instead be taking in migrants from countries like Norway, whose prime minister visited him a day earlier.
The paper quoted him as saying: "Why do we need more Haitians? Take them out."
Senator Lindsey Graham, a South Carolina Republican, was in Thursday's meeting at the White House, but would not comment on the president's reported slur.
What has the White House said?
"Certain Washington politicians choose to fight for foreign countries, but President Trump will always fight for the American people," a statement from White House spokesman Raj Shah said.
"Like other countries that have merit-based immigration, President Trump is fighting for permanent solutions that make our country stronger by welcoming those who can contribute to our society, grow our economy and assimilate into our great nation.
"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."
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What reaction has there been?
UN human rights spokesman Rupert Colville said: "If confirmed these are shocking and shameful comments from the president of the United States, I'm sorry but there is no other word for this but racist."
Mr Colville spoke of a 2016 presidential campaign speech in which Mr Trump called Mexican immigrants criminals and rapists, and his response last year to a white supremacist march that ended in violence in Charlottesville, Virginia, when the president said "both sides" were to blame.
The UN official said such comments went against "universal values the world has been striving for" since the end of World War Two, and opened "the door to humanity's worst side".
In the US, the National Association for the Advancement of Colored People (NAACP) accused the president of falling "deeper and deeper into the rabbit hole of racism and xenophobia".
Mia Love, a Utah Republican and the only Haitian-American in Congress, demanded Mr Trump apologise for the "unkind, divisive, elitist" comments.
Elijah Cummings, a Maryland Democratic lawmaker, tweeted: "I condemn this unforgivable statement and this demeaning of the office of the Presidency."
Another black Democratic lawmaker, Cedric Richmond, said Mr Trump's comments "are further proof that his Make America Great Again agenda is really a Make America White Again agenda".
But one Trump official was quoted by CNN as saying: "Though this might enrage Washington, staffers predict the comment will resonate with his base, much like his attacks on NFL players who kneel during the National Anthem did not alienate it."
How was the slur reported?
The Washington Post broke the story with the word "shithole" in its headline and in the alert that the paper sent out to followers' smartphones.
On US TV, some broadcasters gave content warnings or avoided saying the word altogether. Fox News used asterisks to obscure the offensive word along the bottom of the screen, but CNN and MSNBC carried it in full.
Around the world, journalists reporting in other languages faced the question of how to translate what Mr Trump had said.
- In French, headlines featured "pays de merde", using the expletive to refer to the countries but without the word "hole"
- In Spanish, "países de mierda" was used, similar to the French, as well as "países de porquería", which means "trash countries"
- In German, "Drecksloch" , which literally means dirt hole but like the word used by Mr Trump is considered vulgar
- In Dutch, one newspaper used "achterlijk" (backward) as its headline
- In Japanese, a word that translates as "outdoor toilet" was used
- In Portuguese, one outlet used a word that translates as 'pigsty', while others translated the quote literally