LONDON (Reuters) - Prince Harry could be quizzed for four days in the witness box by lawyers for Rupert Murdoch's News Group Newspapers (NGN) when his lawsuit against the publisher goes to trial next month, London's High Court was told on Tuesday.

King Charles' younger son is suing NGN over alleged unlawful activities carried out by journalists and private investigators working for its papers, the Sun and the defunct News of the World, from 1996 until 2011.

Last month, the court was told by Harry's lawyer that his case would go to trial in January along with one other litigant - former Labour Party deputy leader Tom Watson - after about 40 other claimants settled.

At the start of a hearing on Tuesday to finalise details for the eight-week trial, Anthony Hudson, NGN's lawyer, said he would need four days to question the prince about the 30 articles which he says were based on unlawfully obtained information.

Hudson also said the issue of when Harry, the Duke of Sussex, was aware that he had a case would "require extensive cross-examination", as it is part of NGN's case that the prince had brought his lawsuit too late.

Harry's lawyer David Sherborne said while his client would "relish" four days giving evidence against NGN, one and a half days should suffice.

The trial will consider the specific claims of the fifth-in-line to the throne and Watson as well as generic allegations of wrongdoing by NGN staff, including editors and other senior figures.

NGN has paid out hundreds of millions of pounds to victims of phone-hacking and other unlawful information gathering by the News of the World and settled claims brought by more than 1,300 people.

But it has always rejected allegations of any wrongdoing by staff at the Sun, and no case has previously gone to trial.

"I think one of the reasons why I brought the claim ... is specifically for truth and accountability," Harry said at the New York Times Dealbook Summit last week.

Hudson said those words showed that Harry wanted to turn the trial into a public inquiry.

It will be Harry's second time in the witness box at the High Court, having become the first British royal for 130 years to give evidence in June 2023 as part of his successful litigation against Mirror Group Newspapers.

He received "substantial" damages after the court ruled that his phones had been hacked with the knowledge of Mirror Group Newspapers' senior editors and executives.

As well as the NGN trial, Harry is also suing Associated Newspapers, the publisher of the Daily Mail, for phone-hacking and other unlawful activities along with singer Elton John and five others. That case is due to go to trial in early 2026.