Senior executives of Mirror Group Newspapers authorised widespread illegal activity at their tabloids including the targeting of a British royal, the lawyer for Prince Harry and others suing the publisher said on Thursday.
Harry, King Charles' younger son, and more than 100 others including celebrities and high-profile figures, are suing the publisher of the Daily Mirror, Sunday Mirror and Sunday People.
They allege the papers habitually accessed private information by phone-hacking, deception and other illicit means between 1991 and 2011.
MGN, now owned by Reach (RCH.L), is contesting the allegations, arguing some claims have been brought too late, and rejecting most of the others. It denies any senior figures had knowledge of unlawful acts.
On the second day of the trial at the High Court in London, David Sherborne, the lawyer representing the claimants, said knowledge and involvement in unlawful acts went right to the top of the company.
"At all levels, the defendant's organisation was concealing unlawful activity because it was well aware of how damaging it was," he said.
One of those unlawfully targeted was Prince Michael of Kent, the cousin of the late Queen Elizabeth, Sherborne said, saying the Daily Mirror had run a story in January 1999 which alleged he had financial difficulties, with a large unauthorised overdraft and a 2.5 million pound debt to his bank.
Sherborne told the court this information had been obtained illegally by private investigators accessing the prince's bank account details, citing documented calls between them and one of the journalists involved and subsequent invoices.
When the royal's lawyers complained the story was inaccurate and obtained illegally, the Mirror's then editor, Piers Morgan, replied in a letter the suggestion was a "poor and thinly disguised threat that I will not dignify with comment" and the information had come from an "impeccable source".
Sherborne said the prince's lawyers wrote again, saying that, before the article was published, two "hoax" calls had been made to his bank seeking to confirm his bank account number. MGN later settled the claim and issued an apology.
It was "inconceivable the legal department and Mr Morgan were not aware of the source of this story", Sherborne said.
Morgan, now a high-profile media figure, has always denied any involvement in, or knowledge of, phone-hacking or other illegal activity.
"There is no evidence that I knew anything about any of it," he told the BBC in an interview ahead of the trial.
At the start of the trial on Wednesday, court documents showed that MGN had apologised to Prince Harry for unlawfully seeking information about him and that he was entitled to compensation.
Harry, who is not in court, is due to give evidence himself in person during the seven-week trial in early June, the first British royal to do so since the 19th century, according to local media.
The Mirror case is just one of four the prince, the Duke of Sussex, is currently pursuing against newspapers, saying it was his duty to expose "criminality" committed by the tabloids.
