Kate Middleton and Tony Blair are the latest high-profile royals and politicians to be drawn into a phone-hacking scandal.

The Metropolitan Police is being urged to expand their inquiry into allegations surrounding the News of The World newspaper, to include a notorious private investigator.

In the House of Commons yesterday, Jonathan Rees was accused of targeting politicians, members of the royal family as well as high-level terrorist informers for Rupert Murdoch’s News International, according to The Guardian.

During prime minister’s questions, Tom Watson MP said he had received a letter from Sue Akers, the Met Police deputy assistant commissioner who is leading the probe into phone hacking, which said evidence about Rees maybe outside the terms of reference of her inquiry.

However, David Cameron told the Commons the inquiry should follow where the evidence took it.

The Guardian also claimed other targets of Rees included: Jack Straw when he was home secretary; Alastair Campbell when he was Blair’s media adviser; Kate Middleton when she was Prince William’s girlfriend; the former commissioner of the Met, Sir John Stevens and the governor of the Bank of England.

None of these cases has been confirmed or investigated.

Rees was jailed in 2000 for conspiracy for framing the ex-wife of a client involved in a custody battle to make her appear to be a drug dealer, according to the Financial Times.

Glenn Mulcaire, a News of The World employee, and Clive Goodman, the paper’s royal editor, pleaded guilty to intercepting voicemails of mobile phones belonging to members of Prince William and Prince Harry’s households as well as other high-profile figures.

However, Rees, who ran a private detective agency and was freelance for the News of The World and other newspapers, worked entirely separately to Mulcaire and Goodman.

A News International spokesman told The Guardian: “It is well documented that Jonathan Rees and Southern Investigations worked for a whole variety of newspaper groups.

“With regards to Tom Watson’s specific allegations, we believe these are wholly inaccurate.

“The Met police, with whom we are co-operating fully in Operation Weeting, have not asked us for any information regarding Jonathan Rees.

“We note again that Tom Watson MP made these allegations under parliamentary privilege.”

It comes as the News of The World owner formally apologised in court to Sienna Miller for hacking into several of her mobile phones.

The 29-year-old actress, who was not at London’s High Court, formally settled for £100,000 damages and costs.

News Group newspapers said it was sorry for the “harassment and distress” caused.

The scandal dates back to 2006, when Goodman and Mulcaire were jailed.

Since then, more celebrities and public figures have alleged their phones had been hacked.

News International, owned by Rupert Murdoch, has said it will co-operate fully with the Met Police inquiry.