The Duchess of Cambridge and the former British prime minister are amongst a number of public figures allegedly targeted by private investigator Jonathan Rees, The Guardian reports.
The allegations follow comments made by MP Tom Watson in Parliament yesterday.
He did not name specific individuals, but claimed that Rees had been "illegally targeting members of the royal family, senior politicians and high-level terrorist informers" on behalf of the News International media group.
It is thought that the duchess was targeted before she married Prince William.
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News International denied the allegations in a statement, saying: "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."
News International also added that Rees has worked for a number of different newspaper groups.
A spokesman for Scotland Yard confirmed that "a number of allegations" about apparent privacy intrusions are "currently being considered" but offered no comment on any specific claims.
Sienna Miller successfully sued the News of the World for hacking her phone and received £100,000 ($165,000) in damages last month.
The G.I. Joe actress also received a formal apology from the newspaper.