Prince Charles and Prince Harry are likely to be quizzed as witnesses in a cash for honours investigation launched by Scotland Yard.

The Prince of Wales and his former right-hand man Michael Fawcett were reported to police over a Saudi billionaire who made donations to royal charities, allegedly after he was promised a knighthood and British citizenship.

In a move that could heap further misery on the Queen and Royal Family, the Metropolitan Police on Wednesday announced it had launched a probe.

The Prince of Wales, who presented Mahfouz Marei Mubarak bin Mahfouz with an honorary title at a private ceremony at Buckingham Palace in 2016, has denied knowledge of the alleged deal.

The investigation emerged amid calls for transparency about Prince Andrew’s £12million civil sex case settlement.

It was claimed that the Queen helped Prince Andrew settle the claim by making a £2million donation to his sex abuse accuser’s charity. But ­questions were still being asked about whether public money was used.

A source close to Charles confirmed the future king is willing to speak to the police to help the investigation.

They said: “There has been no request for help from the police so far, but if he is asked to help he will of course do so.”

The allegations centre around ­businessman Mr. Mahfouz donating £1.5million to restoration projects of particular interest to Prince Charles.

Mr. Fawcett, who has since quit as chief executive of Charles’s charity, is alleged to have negotiated with fixers to secure a CBE for the Saudi who was said to be seeking recognition and residency in the UK in return for financial contributions to The Prince’s Foundation.

Prince Harry met Mr. Mahfouz in 2013 and was pictured shaking hands with the billionaire who donated £50,000 to his charity.

In December, the Sunday Times revealed that the pair met at a pub in Chelsea, West London, owned by Mark “Marko” Dyer, a former royal equerry known as Harry’s “second father”, who is said to have brokered the introduction in 2013. They reportedly discussed Sentebale, a charity Harry set up after a gap year in Lesotho, Southern Africa.

In response to the report, the Duke of Sussex issued a rare statement saying he had severed his ties with Mr Mahfouz.

A spokeswoman for Prince Harry said: “The Duke and his advisers, as well as his nonprofit Sentebale, severed ties with Mr Mahfouz and his associates in 2015, no longer accepting further donations to Sentebale and discontinuing any plans for a fundraising event amid growing concerns over his motives.

“The Duke had one planned meeting with this donor nearly eight years ago, did not introduce him to any members of the Royal Family, and expressed concerns about the donor.”

Reacting to the scandal,  Met detective sergeant Steve Morris said: “Both Prince Charles and Prince Harry should be questioned without a doubt.
“It is all part of the investigation, how the donor got to where he is within the charity, that is vital evidence to show the picture of how he has allegedly infiltrated the charity.

“They should both be spoken to at the very least as witnesses. It would involve officers going to their address, or them being invited to a police station to give what’s called a Section 9 statement, purely as a witness at this moment in time.”

A Clarence House spokesman said: “The Prince of Wales had no knowledge of the alleged offer of honours or British citizenship on the basis of donation to his charities.”