LONDON (AP) - The chairman of Prince Charles' charitable foundation has resigned after reports the organization was offered a donation of more than 500,000 pounds ($692,000) from a Russian banker seeking British citizenship.

Douglas Connell stepped down Wednesday after the Sunday Times alleged that Charles wrote a letter to thank the businessman, Dmitry Leus, for the offer last year. The newspaper said Charles suggested that they could meet after the pandemic.

The Scottish Charity Regulator launched an investigation into the matter earlier this week. The report said the charity initially received 100,000 pounds from the Russian, but rejected the total sum after its ethics committee raised concerns about Leus' background.

The allegations followed earlier claims, also reported by the Sunday Times, that the charity's chief executive, Michael Fawcett, helped a Saudi donor secure a knighthood and British citizenship after he gave a large donation.

Fawcett, Charles' former valet, stepped down from the charity role temporarily and an independent investigation was launched.

Connell said Wednesday that he should accept responsibility “if it appears that serious misconduct may have taken place.” The Prince's Foundation said it took the recent allegations seriously and “is committed to the highest ethical standards.”

Charles is president of the foundation but he is not involved with its governance or day-to-day activities.

A spokesman said Charles “fully supports the investigation now under way at the foundation.”