Prince Harry’s phone was hacked while he was studying for his GCSEs, a whistleblower has said.
The whistleblower spoke to Byline Investigates about his time working for the defunct News Of The World tabloid newspaper.
The new claims pre-date the existing timeframe of hacking of the royal’s phone.
The whistleblower told the news site: “As the lead investigator, I was tasked to forensically gather as much intelligence about Prince Harry’s activities in the nocturnal hours, with a view to enhancing the newspaper’s ‘project’.
“The instruction was to monitor communications and to identify any references to drugs.”
The whistleblower said he would clone the identities of mobile phone company workers and use them to access customer accounts.
The admissions come a few months after Prince Harry announced he would sue the owners of The Sun, the News of the World and the Daily Mirror.
As he and his wife Meghan finished off their tour in South Africa last October, Harry made the announcement that he would take legal action over the alleged illegal interception of voicemail messages.
Harry’s lawsuit is believed to include instances that go back to the 2000s. The hacker found no evidence of drug use.
Meghan is pursuing her own legal action against the publisher of the Mail On Sunday and the Mail Online for copyright breach.
In October, a spokeswoman for News Group Newspapers (NGN), the publisher of the Sun and the News of The World, said: "We confirm that a claim has been issued by the Duke of Sussex."
The Royal Family was first swept up in the phone hacking scandal in 2005, when a story emerged about William straining a tendon in his knee.
A complaint from Buckingham Palace sparked a police investigation that opened up thousands of instances of hacking.
In previous court hearings, it emerged that Harry, Prince William and the then Kate Middleton, had all been hacked.
Kate’s messages were hacked 155 times between 2005 and 2006, while William was hacked 35 times and Harry nine times.
News UK and a spokesman for the Sussexes did not comment to Yahoo UK.