The publisher of the Mirror has apologized to Prince Harry at the start of a trial over alleged phone hacking.

Mirror Group Newspapers (MGN) apologized to Harry and others for unlawful information gathering, and said it would never be repeated.

Lawyers representing the prince said he was subjected to the “most intrusive methods of obtaining personal information”.

Harry is one of several high profile figures bringing claims against MGN.

Lawyers argue that executives at the company knew about widespread phone hacking but failed to act.

MGN – which also publishes the Sunday Mirror and Sunday People – admitted that the legal challenge brought by Prince Harry “warrants compensation”.

But the company is set to argue that some of the claims have been brought too late.

A previous hearing was told Harry’s case is that 148 articles published between 1996 and 2010 included information that was allegedly obtained through methods including phone hacking.

Prince Harry is expected to give evidence in June – the first time a senior royal will be a witness in court in modern times – with the High Court hearing set to last six or seven weeks.

The estate of the late singer George Michael and actor Ricky Tomlinson have also brought claims against MGN, with “test cases” – including Harry’s – selected to go to trial from the wider group of claimants.

The other “representative” cases set for trial are that of former Coronation Street actress Nikki Sanderson, comedian Paul Whitehouse’s ex-wife Fiona Wightman and actor Michael Turner.

MGN has previously settled a number of claims against it in relation to stories obtained through unlawful means.

It was also involved in a 2015 trial, the only to take place during the long-running litigation, which saw claims brought by ex-footballer Paul Gascoigne, actress Sadie Frost, and Coronation Street actress Shobna Gulati.

Last month, lawyers for the group said that all the witnesses on their side would give evidence in person, paving the way for Prince Harry to take the stand.

He has become an outspoken critic of the tabloid press and has already appeared in court once this year to listen to legal arguments in another case he is involved in.