LONDON, United Kingdom (AFP)— Prince Harry is on Tuesday expected to take the witness stand in a London court as part of claims against a British tabloid publisher, the latest in his legal battles with the press.

King Charles III's younger son will become the first senior British royal to give evidence in court for more than a century when he testifies against Mirror Group Newspapers (MGN).

He and various other high-profile claimants accuse it of unlawful activities, including phone hacking.

The case is one of several that the 38-year-old prince has brought against British newspaper groups since stepping down from frontline royal duties in early 2020 and eventually relocating to California with his American wife Meghan Markle.

Harry's lawyer David Sherborne told London's High Court on Monday that the prince was targeted by illegal information-gathering even as a young schoolboy and his phone would have been hacked on "multiple occasions".

"No aspect of the young prince's life was safe" from press intrusion, he submitted.

Representing MGN, publisher of The Mirror and The Sunday People tabloids, barrister Andrew Green said there was "no evidence" that Harry's phone was tapped.

The prince had been expected to appear in the courtroom Monday but did not take part in the hearing because of flying to the UK late Sunday after celebrating his daughter Lilibet's second birthday, according to Sherborne.

The case against MGN centres on claims its tabloids conducted unlawful information-gathering to obtain stories about Harry and other claimants, including two TV soap opera actors and the ex-wife of a comedian.

At the start of the trial on May 10, MGN apologised and admitted to "some evidence" of unlawful information-gathering, including for a story about Harry.

But it denied voicemail tapping and also argued that some claims had been brought too late.

Sherborne submitted that "industrial scale" illegal activities were happening at MGN and had been approved by senior executives.

Harry, who is fifth in line to the throne, has had a turbulent relationship with the press and holds the media responsible for the death of his mother Princess Diana, who died in a Paris car crash in 1997 while being pursued by paparazzi.

In television interviews and his explosive memoir "Spare" -- released in January -- Harry hit out at other royals, accusing them of colluding with the press.

In court filings unveiled in April, Harry claimed the royal family as an institution had struck a "secret agreement" with one UK publisher that had prevented him from suing, to avoid a royal entering the witness box.

He also alleged the monarchy wanted to prevent the opening of a "Pandora's Box" of negative coverage that could tarnish the royal brand.

The prince has vowed to spearhead efforts to enforce change on Britain's tabloid media, and the MGN trial is one of several ongoing legal battles he has launched against the press.

They include joint legal action against Associated Newspapers (ANL), publisher of the Daily Mail, over alleged breaches of privacy.

The California-based prince made a surprise appearance at the High Court in March to hear legal arguments in the case, but did not give in-person evidence.

His testimony on Tuesday will be the first time a senior royal has given evidence in court since Edward VII, who took the stand in an 1890 slander trial before becoming monarch.

Charles's sister Princess Anne became the first member of the current royal family to be convicted of a criminal offence after one of her dogs bit two children in 2002.

She pleaded guilty to an offence under the Dangerous Dogs Act so was not required to give evidence in court.