The Tories have been urged to launch a probe after it emerged a major donor was named in an international money-laundering case.
Tycoon Javad Marandi, who was awarded an OBE for business and philanthropy in 2019, "vehemently" denies wrongdoing and isn't subject to criminal sanction.
He was identified after losing a 19-month legal battle with the BBC to remain anonymous, which the broadcaster hailed as a milestone for freedom of the press.
