Kate Middleton allegedly had her bank account hacked by a private detective working for the News of the World, Britain's Daily Telegraph reports.
The Duchess of Cambridge is among a number of high profile people targeted by Jonathan Rees, with former Prime Minister Tony Blair, former Cabinet minister Jack Straw, the Duke and Duchess of Kent and Metropolitan Police assistant commissioner John Yates, who headed the phone hacking inquiry.
The allegations against Mr Rees were made by MP Tom Watson, who told the House of Commons yesterday the Duchess of Cambridge's account was hacked by the investigator in 2005 when she was dating Prince William, who she married earlier this year.
Mr Watson said Scotland Yard had evidence against the investigator but have said it falls outside the scope of their investigation.
The Telegraph reported Scotland Yard detectives are understood to have got in contact with Kate to warn her that her bank details may have been accessed.
A St James's Palace spokesman told the paper they were unable to comment.
Mr Rees was this year cleared of the 1987 murder of Daniel Morgan, however after his acquittal it was revealed Mr Rees had worked as a private investigator for a number of media organisations.
A spokesman for News International, the News of the World's parent company, told the Telegraph that Mr Watson's allegations were "wholly inaccurate".
Mr Rees solicitor did not respond to enquires for the Telegraph.
- NZ HERALD STAFF