Joe Biden’s presidential campaign has distanced itself from his assertions he was arrested in South Africa while trying to visit Nelson Mandela.
Mr Biden has said he was arrested during a trip to the country in the 1970s, when it was under apartheid.
But a deputy campaign manager told reporters he had been referring to an episode where he was separated from black colleagues at an airport.
He is third in the race for the Democrats’ presidential nomination.
He first made the assertion at an event in South Carolina earlier this month, reminiscing about his personal history with Mandela, South Africa’s first black president who died in 2013.
Mr Biden – at the time a senator for Delaware – said he had been visiting the country with a delegation of American officials, and had planned to visit Mandela in prison.
But during the trip, Mr Biden said he had “had the great honour of being arrested with our UN ambassador on the streets of Soweto” while trying to reach the civil rights leader on Robben Island. The town of Soweto is more than 760 miles (1,223km) from Robben Island.
At a black history awards brunch in Las Vegas last week, he also said Mandela had thanked him for his efforts.
“He threw his arms around me and said, ‘I want to say thank you,'” Mr Biden told onlookers. “I said, ‘What are you thanking me for, Mr President?’ He said: ‘You tried to see me. You got arrested trying to see me.'”
Mr Biden’s account of what happened has been rebuffed by Andrew Young, a former US ambassador to the UN, who says he travelled with Mr Biden to South Africa.
Local media have also failed to find any evidence of an arrest being made.
On Tuesday Mr Biden’s deputy campaign manager, Kate Bedingfield, told reporters Mr Biden had been referring to an incident when “he was separated from his party at Johannesburg airport”.
When a journalist noted that being separated did not equate with an arrest, Ms Bedingfield repeated that it had been a “separation”.
“They, he was not allowed to go through the same door that the – the rest of the party he was with,” said Ms Bedingfield. “Obviously, it was apartheid South Africa. There was a white door, there was a black door. He did not want to go through the white door and have the rest of the party go through the black door. He was separated.”
The account echoes earlier comments made by Mr Biden, but a statement he made in 2013 gives a different account of his trip.
“When I exited the plane I was directed to one side of the tarmac, while the African American congressmen travelling with me were sent to the other side,” said Mr Biden. “I refused to break off, and the officials finally relented.”
He has faced scrutiny for his verbal gaffes and his long and sometimes controversial political career, including his vote in favour of the Iraq war.
Republicans have been hammering away at him for his son’s lucrative board position with a Ukrainian natural gas firm when he was vice-president and in charge of American-Ukrainian relations. The issue came up in the Trump impeachment case.
Vermont Senator Bernie Sanders currently holds the most delegates for the Democrats’ presidential nomination, followed by Indiana mayor Pete Buttigieg and Mr Biden.