“The Metropolitan Police Service has launched an investigation into allegations of offences under the Honours (Prevention of Abuses) Act 1925,” the police said in a statement.
Scotland Yard, as the London police force is popularly known, added that the decision follows an assessment of a September 2021 letter related to media reporting "alleging offers of help were made to secure honours and citizenship for a Saudi national".
The Prince Foundation's chief executive, Michael Fawcett, stepped down in October amid claims that he had promised to help Saudi donor Mahfouz Marei Mubarak bin Mahfouz secure a Commander of the Order of the British Empire award and British citizenship.
The London Metropolitan Police said, "there have been no arrests or interviews under caution".
The probe into a foundation run by the heir to the UK throne comes just hours after his brother Andrew settled out of court a civil sex abuse case with an Australian-American woman who was accusing him of sexually assaulting her when she was 17.