Clarence House is facing fresh questions over further revelations in the royal “cash-for-honours” scandal involving middlemen who reportedly took cuts for setting up meetings between wealthy donors and the Prince of Wales.

Prince Charles “met at least nine times” with William Bortrick, the alleged fixer at the heart of the claims, who is said to have received thousands of pounds to secure an honour for a Saudi billionaire and brokered a personal thank you letter from Charles to a Russian donor, the Sunday Times reported.

Clarence House has previously said it had “no knowledge” of the practice of paid intermediaries arranging access to the royal family or honours in exchange for donations to the prince’s charities.

Meanwhile, the Mail on Sunday reported that Charles met Bruno Wang, who describes himself as a Chinese philanthropist and donated £500,000 to the prince’s charity, the Prince’s Foundation.

The newspaper claimed that Wang is wanted in Taiwan for alleged money laundering and being a fugitive from justice, allegations he strongly denies, and drew comparisons between Wang and the Russian banker Dmitry Leus.

Leus was likewise accused of money laundering and made a donation of £500,000 to the foundation. Leus’s conviction was overturned.

The Russian banker reportedly received two invitations to private events at Charles’s royal residences in Scotland, allegedly secured by Bortrick. They were both cancelled because of the pandemic and concerns about the donor’s past.

The allegations have prompted an investigation at the Prince’s Foundation which has led to Michael Fawcett temporarily stepping down as chief executive. Fawcett said he fully supported the investigation. Douglas Connell, the chair of the Prince’s Foundation, also resigned, citing evidence of possible “rogue activity” and “serious misconduct” of which he said he had no knowledge.

The Sunday Times reported that Charles met Bortrick in England, Scotland and Saudi Arabia over the past seven years. Bortrick attended donor dinners hosted by Charles at Dumfries House, the royal residence in Ayrshire; saw the prince in London at Clarence House, St James’s Palace and Buckingham Palace; and met the prince over tea and sandwiches at the British embassy in Riyadh.

In summer 2020, Charles, 72, and Bortrick, 48, met at the Castle of Mey, the late Queen Mother’s former home in Caithness, the newspaper reported.

Weeks before this meeting, the paper claims, Bortrick brokered a six-figure donation to the charity from Leus in exchange for a meeting with the prince. He received a £5,000 (€5,860) cut of the donation for “expenses”.

On 5 August, shortly after the meeting, Bortrick wrote to the Russian: “I have just had an excellent private visit with HRH the Prince of Wales who appreciates your generosity and asked me to send his personal good wishes to you.”

The Prince’s Foundation declined to comment on either articles when approached for comment.

A spokesperson for Clarence House told the Guardian: “The Prince of Wales has no knowledge of the alleged offer of honours or British citizenship on the basis of donation to his charities and fully supports the independent investigation now under way by the Prince’s Foundation.”

Bortrick is the editor and owner of Burke’s Peerage, a genealogical publication that chronicles the aristocracy. He has used the publishing company behind it to receive payments for consultancy services to ultra-wealthy individuals seeking access to the British establishment.

The Guardian attempted to contact Bortrick through Burke’s Peerage. A spokesperson for Bortrick told the Sunday Times: “Mr Bortrick is a proud supporter of the Prince’s Foundation. In his dedication to the foundation, Mr Bortrick has introduced a number of potential benefactors to the Prince’s Foundation.”

They said he had met the prince only “in a group setting and never in private”.

Bruno Wang, who lives in the Cayman Islands, is being pursued in Taiwan for the millions made in a 30-year-old warships deal overseen by his now deceased father, Andrew Wang.

A spokesperson for Wang said Bruno was never involved in the original transaction.

He said: “These 30-year-old accusations in Taiwan against his deceased father are politically motivated and without foundation. When they were made about his father before the Cayman court in 2014, the honourable chief justice, Anthony Smellie, dismissed them as not only ‘wholly unintelligible’ but ‘scandalous and vexatious’.”

He added: “Bruno is committed to supporting charitable endeavours that promote art, wellness and social inclusion.”