Prince Harry and his wife Meghan have blacklisted four major British tabloid newspapers because of their reporting, in the latest escalation of their public battle with the media.

The Duke and Duchess of Sussex accused The Sun, Daily Mirror, Daily Mail and Daily Express of publishing stories that were "distorted, false and invasive beyond reason".

The couple, who have quit frontline royal duties and moved to North America, outlined their new policy of "no corroboration and zero engagement" in a scathing letter to editors of the titles.

The Guardian newspaper called it an "unprecedented attack on a large part of the media" while former tabloid bosses criticised the timing of the announcement, as the world grapples with the fall-out from the coronavirus pandemic.

Harry and Meghan have intensified their war with the media since their high-profile wedding in 2018, hitting out at what they say have been intrusive and unfair reports about them.

The prince has brought court action over allegedly intercepted voicemails and Meghan is suing over the publication of a "private" letter to her father in August 2018.

A preliminary hearing in her case against Associated Newspapers, which publishes the Mail on Sunday and MailOnline, is due to be held at the High Court in London on Friday.

Details of communications between the couple and Thomas Markle were filed in court on Monday, revealing the pair pleaded with him in text messages not to speak to the media before their wedding.

In one text message dated May 14, 2018, Harry asks him to call back and warned him that "'going public' will only make the situation worse".

Thomas Markle became the centre of a tabloid furore after allegedly staging paparazzi style photographs of himself for money.

He later dropped out of the glittering wedding ceremony at Windsor Castle on health grounds but also said he did not want to "embarrass the royal family or his daughter".

Prince Harry and his wife Meghan have repeatedly complained about intrusive media
Prince Harry and his wife Meghan have repeatedly complained about intrusive media POOL / Jeremy Selwyn

Harry blamed the media for the furore and insisted he and his wife were not angry.

But he again cautioned: "Any speaking to the press WILL backfire, trust me Tom. Only we can help u, as we have been trying from day 1."

Meghan's lawyers maintain that a subsequent letter, parts of which were published in the Mail on Sunday, were "obviously private" and detailed her "intimate thoughts and feelings" about her father's health and relationship with him at the time.

They claim the newspaper "chose to deliberately omit or suppress" parts of the letter, which "intentionally distorted or manipulated" its meaning, and gave her no warning it was due to be published.

Associated Newspapers denies the contents were private or confidential. Thomas Markle has said he felt pressured to share the letter after its contents were misrepresented in a magazine article.

Harry and Meghan's letter to the British tabloids lays bare what they feel about newspaper coverage but insisted they were not trying to put themselves above scrutiny.

"It's not about shutting down public conversation or censoring accurate reporting," they said.

Instead, they said they did not want to be used as "currency for an economy of clickbait and distortion" .

More broadly, they said there was a "real human cost" of "salacious gossip" purely to sell newspapers.

The pair said their new policy did not apply to all media and they would continue to work with journalists around the world.

The Society of Editors, however, said their "actions here amount to censorship" while former Mirror and News of the World editor Piers Morgan said it smacked of self-centredness.

"Imagine thinking anyone cares about their hurt little me-me-me egos as health workers around the world are dying at work?" he tweeted.

David Yelland, a former editor of The Sun, told BBC radio the move was ill-advised, calling the letter "one of the worst pieces of communication" he had ever seen.