LONDON (AP) — A former top aide to Prince Charles has quit as chief executive of the heir to the throne’s charitable foundation after allegations he offered to help a wealthy Saudi businessman who made a large donation secure a knighthood and British citizenship.

The Prince’s Foundation said late Thursday that Michael Fawcett had resigned.

Charles’ Clarence House Office said it would no longer use the services of Fawcett or his party planning company, Premier Mode.

Fawcett, Charles’ former valet, stepped down from the charity role temporarily in September and an independent investigation was launched after the Sunday Times newspaper reported the allegations.

His resignation comes after the Mail on Sunday published a letter from 2017 in which Fawcett reportedly wrote that he was willing to make an application to get businessman Mahfouz Marei Mubarak bin Mahfouz an honorary knighthood and support his application for citizenship in response to “the most recent and anticipated support” for the charity.

Mahfouz has denied any wrongdoing.

The Prince’s Foundation said when the allegations emerged that it took them 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.