Britain's Prince William settled a phone-hacking claim against Rupert Murdoch's UK newspaper arm in 2020 for a “very large sum” after a secret deal struck with Buckingham Palace, lawyers for the heir's brother Prince Harry said in court documents.

Harry, the younger son of King Charles, is suing News Group Newspapers (NGN) at the High Court in London for multiple unlawful acts allegedly committed on behalf of its Sun and now defunct News of the World tabloids from the mid-1990s until 2016.

He accuses those acting for the papers of phone-hacking and obtaining private information about him by deception, including getting hold of his wife Meghan's social security number.

NGN, which has paid out millions after a number of journalists at the News of the World were jailed for phone-hacking leading to Murdoch closing it down, is seeking to have his claim dismissed, arguing he should have brought it sooner.

It also denies anyone from the Sun was involved in any unlawful activity.

In a submission on his behalf, Harry's legal team said a deal had been agreed between NGN and the “institution” - Buckingham Palace - to hold off any claims until other outstanding phone-hacking litigation was settled.

"It is important to bear in mind that in responding to this bid by NGN to prevent his claims going to trial, the claimant has had to make public the details of this secret agreement, as well as the fact that his brother, His Royal Highness, Prince William, has recently settled his claim against NGN behind the scenes," the document said.

It said NGN had settled with William “for a very large sum of money in 2020”.

The document quoted from Harry's witness statement in which the prince said the deal was struck to“avoid the situation where a member of the royal family would have to sit in the witness box and recount the specific details of the private and highly sensitive voicemails that had been intercepted”.

Harry said Buckingham Palace “wanted to avoid at all costs” the reputational damage caused by publication in the 1990s of details of an “intimate telephone conversation” between Charles and the now Queen Consort Camilla, when his father was still married to his mother Princess Diana.

As part of a chronology detailing an exchange of letters between the Palace and NGN, the document said Harry's grandmother, the late Queen Elizabeth, had been involved in discussions and in 2017 had given her permission for him to pursue his case.