International organisations including the United Nations (UN) and the African Union (AU), politicians and ordinary Africans and Caribbeans are outraged over US President Donald Trump's latest racist remarks.

The president criticised immigration to his country from El Salvador, Haiti and the African continent, by calling the group "shithole countries", according to the US media.

"Why are we having all these people from shithole countries come here?" Trump asked at a meeting with congress members, reports said on Thursday, citing people with knowledge on the conversation.

Trump suggested the US should instead focus its immigrant entry policy on countries such as Norway, according to the reports.

Rupert Colville, spokesperson of the UN human rights office, said: "You cannot dismiss entire countries and continents as shitholes ... I'm sorry, but there's no other word one can use but racist."

Colville said the story wasn't "just a story about vulgar language, it's about opening the door to humanity's worst side".

The African Union said it was "frankly alarmed".

"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," said AU spokesperson Ebba Kalondo.

South Africa's ruling African National Congress party said Trump's comments were "extremely offensive", with a spokesperson saying the party would never deign to make such derogatory remarks.

Morocco-based Africa analyst Adama Gaye told Al Jazeera: "Trump has shown a continuous display of racism towards Africa [and people from poor nations]."

Following the publication of the media reports, the White House issued a statement in which it did not directly challenge the authenticity of the comments.

"Certain Washington politicians choose to fight for foreign countries, but President Trump will always fight for the American people," the White House said.

The development came as the US president also came under fire for rejecting an invite to open a new US embassy in London.

Many took to social media to condemn the president.

Democratic State Senator Linda Dorcena Forry said on Twitter: "I have to first express how demoralising & upsetting it is to have to register my outrage again and again over hateful remarks made by my own president."

She then posted a statement saying: "I'm very disappointed in us, the people of the United States, who saw fit to elect an ignorant, mean-spirited, white supremacist to the most powerful office in the world."

Writer Wajahat Ali said in a tweet: "In just 11 days, Trump has insulted Pakistan, a country of 200-million, Haiti (11-million), El Salvador (6-million), the entire continent of Africa (which is not a country & has 1.2-billion) & millions of Americans. So, about 1.5-billion people. 20% of the world. Week isn't over."

A Twitter user, apparently from in Haiti, posted the photos of natural beauty in his country, calling Trump a #ShitHolePresident!"

Journalist Jacqueline Charles followed the suit, posting an apparent view in Haiti. She wrote: "Who knew I had been going to a shithole all of these years."

Twitter user Ryan Knight suggested that Republicans insist on claiming Trump is not a racist, although his actions prove them wrong.

Meanwhile, a Norwegian - @Shkurten - publicly rejected Trump's offer to move to the US, saying: "I live in Norway and would never move to USA. We have health care, free higher education, 5 weeks vacation, 8 hours work a day. No thanks Trump."

Shannon Watts, an activist working to end gun violence, tweeted: "Trump's guide to diversity. Africa: Array of shithole countries. Haitians: Have AIDS. Nigerians: Live in huts. Puerto Ricans: Lazy. Black Americans: Ingrates. Mexicans: Criminals and rapists. Muslims: Evil terrorists. Women: Treat them like shit. White supremacists: VERY FINE PEOPLE."