Officers said the decision followed advice from prosecutors and consideration of the information received to date.

It launched an investigation in February last year following a series of newspaper articles accusing former close confidant to the King, Michael Fawcett, of promising to help a Saudi billionaire donor achieve British citizenship and a knighthood.

Anti-monarchy group Republic made a formal complaint about Charles and Mr Fawcett to the police in September 2021.

Mr Fawcett resigned as chief executive of The Prince's Foundation two months later amid the allegations.

Businessman Mahfouz Marei Mubarak bin Mahfouz is reported to have donated large sums to restoration projects of particular interest to Charles.

Mr Mahfouz is said to deny any wrongdoing.

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In a statement, the Met said that "nobody [was] arrested or charged during the course of this investigation".

It added that it had liaised with the King's charity and contacted those who were believed to hold relevant information to the case.

It also said: "As part of the investigation, the Special Enquiry Team [SET] obtained court production orders, spoke with a number of witnesses and reviewed in excess of 200 documents.

"A file was passed to the Crown Prosecution Service [CPS] on 31 October 2022 for early investigative advice. Offences under the Honours [Prevention of Abuses] Act 1925 and Bribery Act 2010 were considered.

"With the benefit of the CPS's early investigative advice, and after careful consideration of the information received as a result of the investigation to date, the Met has concluded that no further action will be taken in this matter.

"Should any new information or evidence come to light that requires further assessment, this will be carried out by the Met's SET."

A spokesperson for Buckingham Palace said: "We have noted the decision of the Metropolitan Police Service. All other enquiries are a matter for The Prince's Foundation."

The Prince's Foundation was established in 1986 by Charles with a focus on a more sustainable world.

Charles is president of the foundation but not involved with its governance, with the charity's trustees overseeing its day-to-day activities.