South African President Cyril Ramaphosa is to repay $35,000 (£27,300) given to his leadership campaign by a firm accused of corruption.
The donor, a firm called Bosasa, has won lucrative government contracts but is under investigation.
Mr Ramaphosa initially told MPs the money had been paid to his son, Andile, for consultancy work for Bosasa.
By later admitting it was a donation, he undermined his own anti-corruption fight, the BBC's Will Ross reports.
The controversy is a setback for a president who has vowed to fight corruption, our Africa editor adds.
Mr Ramaphosa also ordered a review of all payments to his campaign for the leadership of the African National Congress (ANC).
How did this all unfold?
Answering questions in parliament on 6 November, Mr Ramaphosa said money paid to his son by Bosasa (which is now named African Global Operations) had been for legitimate business between the company and Andile.
Then, in a written clarification to parliament this week, he said he had been subsequently informed that the payment did not relate to his son but had been paid into a fund used for his leadership campaign.
"The donation was made without my knowledge," Mr Ramaphosa wrote. "I was not aware of the existence of the donation at the time that I answered the question."
On Saturday, AFP news agency reports, ANC spokesman Zizi Kodwa told state media the president had "decided voluntarily that he will pay back the said amount".
How embarrassing is this for Ramaphosa?
Mmusi Maimane, leader of the opposition Democratic Alliance, has said the Bosasa payment looks "suspiciously like all other ANC government corruption deals".
Since taking over from Jacob Zuma, who stepped down in February in the face of mounting corruption allegations, Mr Ramaphosa has campaigned for probity in public life.
Just this month, he described the corruption plaguing South Africa as an "amoeba" with "tentacles all over".
Acknowledging that South Africans were angry and needed to see senior government officials tried and sent to prison, he compared the current situation to that of a rape victim forced to watch her attacker go unpunished.