The Duke of Sussex is bringing a legal case alongside six other claimants, including Sir Elton John.
Prince Harry says he is determined to hold the publisher of the Mail newspapers to account as he says he is “deeply concerned” by their “unchecked power, influence and criminality”.
His witness statement was disclosed as part of his privacy case against Associated Newspapers.
In it, he also claimed he was kept out of Royal Family discussions about taking legal action on phone hacking.
He attended the High Court for a second day of legal arguments on Tuesday.
The Duke of Sussex and six other claimants, including Sir Elton John and Baroness Doreen Lawrence – the mother of murdered teenager Stephen Lawrence – claim their personal information was obtained illegally and used as material for Daily Mail and Mail on Sunday stories.
Associated Newspapers has dismissed the claims as “preposterous smears” based on a “fishing expedition”.
In the duke’s statement, he criticises attempts by the publisher in court this week to have the case thrown out for legal reasons.
“Unfair is not a big enough word to describe the fact that Associated is trying at this early stage to prevent me from bringing my claim,” the statement reads.
“If the most influential and popular newspaper in the UK can evade justice without there being a trial of my claims, then what does that say about the industry as a whole and the consequences for our great country.
“I am bringing this claim because I love my country and I remain deeply concerned by the unchecked power, influence and criminality of Associated.”
The statement details stories the duke claims were based on private information which had been obtained illegally.
They include reports about his relationships with two girlfriends.
He also criticises a story about his reaction, along with that of his brother William, to the publication of pictures of his dying mother in the Italian media.
“It is really disgusting”, he says, with a “crude headline” and “explicit reference to a phone call”.
“My brother and I were relatively young at the time (I was just 21) and we were having private conversations about photographs of our dead mother which had been put into the public domain.”
In his witness statement, Prince Harry said the Royal Family – which he referred to as the Institution – had been withholding information from him about the possibility of taking legal action in response to media intrusions.
He said he only started talking to a senior lawyer for the Royal Family when he began dating his now wife and “defamatory stories” were published.
The prince eventually became aware he could take legal action over phone hacking in 2018, he says.
“The Institution made it clear that we did not need to know anything about phone hacking and it was made clear to me that the Royal Family did not sit in the witness box because that could open up a can of worms,” he said.
Fellow claimant Sir Elton John has meanwhile accused a private investigator of tapping his home phone and that of his gardener.
He said it was a “violation of our home and the safety of our children and loved ones.”
Sir Elton is claiming damages in relation to 10 articles for which he says the Mail titles “misused information which they stole from our family and friends”.
In his witness statement, he said the Mail exploited “love, connection, trust and bonds to find out information shared in confidence”.
Sir Elton’s case against Associated Newspapers includes the claim that a private investigator obtained details of his medical conditions, including that he had “collapsed on a plane”.
His husband, David Furnish, is also making claims in the High Court legal action.
His statement reveals the couple were informed by the actor Liz Hurley of the allegation that their live phone calls had been intercepted by an investigator working for the Mail on Sunday.
She said the investigator appeared to know that Sir Elton did not have his own mobile phone and used several landlines.
Ms Hurley alleged that her calls had also been tapped.
Baroness Lawrence claims private investigators working for the Daily Mail tapped her home phone and hacked her voicemails.
In her own statement to the High Court, she also accused the newspaper of commissioning investigators to monitor her bank accounts and phone bills.
She says she trusted the Daily Mail, which had strongly campaigned for justice for her family, but concluded: “I was played for a fool.”
Associated Newspapers rejected her allegations as “appalling and utterly groundless smears”.
The publisher said the claims were based on the word of private investigator Jonathan Rees, who has served a prison sentence for perverting the course of justice.
In a statement last year, Associated said: “It is deeply saddening that whoever is cynically and unscrupulously orchestrating these claims appears to have persuaded Baroness Lawrence – for whom the Mail has the greatest respect and admiration – to endorse the word of someone who is such a manifestly discredited and untrustworthy liar.”
But Baroness Lawrence said in her witness statement, disclosed by the court, that she feared the actions of private investigators may have disrupted investigations into Stephen’s murder.
In her statement, she said: “We developed good relationships with the press and by February 1997 we aligned ourselves with the Daily Mail and who always held themselves out to be the guardians of truth and justice, the people who fight corruption and who hold the bad people accountable and who really cared about the fact my son’s killers had walked free.”
But upon discovering the alleged use of private investigators, she said there had been a “level of trust” and “the betrayal I felt when that was taken away and I realised it had all been false was intense”.
She added: “I cannot think of any act or conduct lower than stealing and exploiting information from a murder and from a mother who buried her son, and by people who pretended to be my friends.
“It has been a new trauma and injustice for me.”
Allegations in the case against Associated Newspapers include phone tapping, “hacking” of voicemail messages and the use of private investigators to obtain personal data.
More than 70 journalists have been implicated by the allegations made by seven claimants – Prince Harry, Sir Elton John and his husband David Furnish, Sadie Frost, Liz Hurley, Baroness Doreen Lawrence and Sir Simon Hughes.
Their names cannot be reported for legal reasons.
Legal arguments on Tuesday centred on ledgers setting out payments made by Associated Newspapers (ANL) to 19 private investigators in the past, alleged to have been working for the journalists.
The seven claimants say these were for large sums of money and are proof that illegal methods were being used to gather information about them.
The ledgers were disclosed to the Leveson Inquiry into press standards in 2011.
ANL is trying to get part of the case struck out because, it says, the Leveson files cannot be used in other cases, due to confidentiality rules.
The company also says that two barristers in this case, and Sir Simon Hughes, were closely involved in the Leveson Inquiry and gave “undertakings” not to disclose documents they received.
Barristers for ANL told the court these restrictions would have to be removed by the government if the evidence was to be used in the current case. This has not happened and they said sections of the case relying on the ledgers should therefore be struck out.
But David Sherborne, representing the seven who are suing Associated, told the judge, Mr Justice Nicklin, that the ledgers had in fact been obtained by an investigative journalist, not from the Leveson Inquiry.
As a leading barrister at the Leveson Inquiry, representing victims of press intrusion, he had personally agreed not to disclose confidential information.
But he said that undertaking ended when the inquiry report was published in 2012.
The court also released the witness statement of private investigator Gavin Burrows, who denied all allegations that he hacked phones, tapped landlines, or bugged cars on behalf of the Daily Mail or Mail on Sunday.
Addressing the specific allegations made by Prince Harry, Baroness Lawrence, Elton John, David Furnish, Sadie Frost and Liz Hurley, he said: “I was not instructed or commissioned by the Mail on Sunday or the Daily Mail to conduct unlawful information gathering.”
Two other private investigators have also made statements to the court admitting their role in supplying illegally-obtained information to journalists at the Daily Mail and Mail on Sunday.