US President Donald Trump has insisted he is "not a racist" despite reports he made derogatory comments about immigrants from Haiti and Africa.

Questioned by a reporter in Florida following reports that he had said Haiti and Africa were "shithole countries," President Trump said: "No. I'm not a racist. I'm the least racist person you will ever interview."

The president also denied making the comments attributed to him in a closed-door meeting of lawmakers discussing immigration - but did not go into specifics about what he did or did not say.

"Did you see what various senators in the room said about my comments?" he said to the reporter. "They weren't made."

On Friday, President Trump tweeted a convoluted denial about his alleged choice of words, which triggered a global firestorm of criticism.

But Democratic Senator Dick Durbin, who attended the lawmakers' meeting, said that "shithole" was the "exact word used by the president, not just once but repeatedly."

"He said these hate filled things and he said them repeatedly," Senator Durbin added in a TV interview.

The White House did not deny that President Trump had said the slur.

On Friday, the African Union expressed "dismay and outrage" at the reports and demanded that President Trump apologise.

After an emergency UN session, the group of 54 African ambassadors said in a statement: "The group is extremely appalled at, and strongly condemns the outrageous, racist and xenophobic remarks by the president of the United States of America as widely reported by the media."

A confidant of President Trump has told The Associated Press that the President spent Thursday evening calling friends and outside advisers to judge their reaction to his remarks.

President Trump was not apologetic and denied he was racist, instead blaming the media for distorting his meaning, said the confidant.