Ronald Reagan's daughter says there is "no defence or suitable explanation" for her father calling African delegates "monkeys" in a 1971 phone conversation with the then-US President.
In a recently released audio recording from 1971, the then-California Governor can be heard disparaging African delegates to the United Nations as being "still uncomfortable wearing shoes" during a phone call with US President Richard Nixon.
The previously undisclosed recording followed a move by the UN to expel Taiwan, something the United States had opposed.
Mr Reagan had been venting his frustration with the delegates who voted against the US before being heard saying:
"To see those monkeys from those African countries, damn them," he says.
"They are still uncomfortable wearing shoes."
Nixon can be heard laughing hard.
In other recordings, Mr Nixon goes on to recount his conversation with Mr Reagan to others when discussing the UN vote.
The conversation with Mr Reagan was published this week by the Atlantic magazine in an article written by Tim Naftali, a history professor at New York University and former director of the Nixon Presidential Library.
After Mr Reagan's death in 2004, Professor Naftali was successful in getting the National Archives to release the full recording.
According to The New York Times, Professor Naftali said the National Archives had withheld part of the recording to protect Mr Reagan's privacy.
"It was worse than I expected," Professor Naftali told The Washington Post, referring to the audio on the tape.
"It was the combination of the slur by Reagan and then Nixon's repeating it, not once but twice in later conversations."
What did his daughter say?
In response, Patti Davis wrote in an opinion piece for the Washington Post there was "no defence" for the comments her father made.
"I wanted to immediately go back in time to before I heard my father's voice saying those words," she said.
"There is no defence, no rationalisation, no suitable explanation for what my father said on that taped phone conversation."
She also wrote, "I can't tell you about the man who was on the phone with Richard Nixon that day in 1971".
"He's not a man I knew."
But she did point out Mr Reagan stood up against segregation when he played football in college and refused to accept membership to a ritzy LA country club because the club "didn't allow Jews or African Americans".
"If he said that 50 years ago, he shouldn't have," Melissa Giller, a spokeswoman for the Ronald Reagan Presidential Foundation and Institute, said in a statement to the New York Times.
"And he would be the first person to apologise."
Professor Naftali has said the timing of the recordings' release this month was a coincidence that offered important historical context.
Recently, US President Donald Trump has been criticised for comments he made about four Democratic congresswomen, telling them to go back to their home countries.
That was followed up by an attack on prominent African-American politician Elijah Cummings, in which Mr Trump described Baltimore as a "disgusting, rat and rodent-infested mess".
Mr Reagan was California governor from 1967 to 1975, and US president between 1981 and 1989. He died in 2004.
