A British tabloid has apologised to Prince Harry on the first day of a new phone-hacking trial for one instance of unlawfully seeking information about the young royal 20 years ago.

Prince Harry and some 100 celebrities including actors, sports stars, singers and TV personalities, are suing Mirror Group Newspapers for widespread phone-hacking, deception and other illicit means between 1991 and 2011.

The prince is due to take to the witness stand in June, the first British royal to do so since the 19th century, according to local media.

In court documents published on the trial’s first day on Wednesday (local time), the newspaper group apologised for one instance of hiring a private investigator to gather information about the Duke of Sussex at a London nightclub in 2004.

Mirror Group, owned by Reach, said it “unreservedly apologises and accepts that [Prince Harry] is entitled to appropriate compensation”.

In a witness statement on the opening day, the prince blamed media intrusions for the break-up of his relationship with on-off girlfriend Chelsy Davy, whom he dated between 2004 and 2010.

Ms Davy decided “a royal life was not for her” after being subjected to repeated harassment, the duke’s lawyers alleged.

“Every time he was in a relationship, or even a rumoured relationship, that whole person’s family, and often their friends, would be ‘dragged into the chaos’ and find themselves the subject of unlawful activity on the part of MGN,” lawyers said.

In one example, journalists allegedly booked into a hotel on a small island off Mozambique where the couple had escaped for “peace and quiet”.

The lawyers said Ms Davy was targeted for voicemail interception between 2007 and 2009.

Cover-up

The claimants say unlawful behaviour at the Daily Mirror, Sunday Mirror and Sunday People had occurred with the full knowledge of senior executives who they say failed to stop it and actively covered it up.

MGN contests the allegations, saying some claims have been brought too late, and there was no evidence Prince Harry was a victim of hacking.

It denies any senior figures had knowledge of unlawful acts.

Prince Harry, who was not in court in London for the start of the hearing, has been selected as one of four test cases for the seven-week trial.

“Prince or not, the blatantly unlawful and illegal methods that were used by the defendant … was quite frankly appalling,” David Sherborne, the lawyer representing the King’s younger son and the other claimants said.

“No one should have been subjected to that.”

The trial begins just days after his father’s coronation on Saturday, where Prince Harry appeared briefly for the ceremony at London’s Westminster Abbey and played no formal role.

He is believed to have returned immediately to California, where his son Prince Archie was celebrating his fourth birthday.

The Mirror case is just one of four that Prince Harry is pursuing against newspapers, saying it was his duty to expose “criminality” committed by the tabloids on behalf of those without the same resources as he has.

In March, he attended court in person to hear lawyers for Associated, which publishes the Daily Mail and Mail on Sunday, seek to throw out a case brought by him and other high-profile figures such as singer Elton John.

He is also pursuing a phone-hacking case against Rupert Murdoch’s News Group Newspapers and is also suing Associated for libel. A decision on whether he can win that case without a trial is expected soon.

All the publishers have promised to rigorously fight the claims.

Since stepping down from their royal roles in 2020, Prince Harry and his wife Meghan Markle have lashed out at both the press and the palace, including those working for his brother Prince William and his stepmother, the Queen, saying they had colluded in media “lies”.

In court submissions, MGN said many of the 147 stories Prince Harry claims must have come by unlawful means had in fact been briefed by aides working for the royals, including one of his father’s former press secretaries.