Amid an unprecedented feud with the BBC, the British royal family has issued a strong statement blasting a new documentary that claims Prince William and Prince Harry's staff had a briefing war against each other during the latter's exit as a working royal.

In a rare move, Queen Elizabeth II's office Buckingham Palace, Prince of Wales's Office Clarence House, and The Duke of Cambridge's office Kensington Palace issued a joint statement accusing BBC of giving credibility to "overblown and unfounded claims" in the programme. The two-part BBC2 show, titled "The Princes and The Press," aired on the network on Tuesday, containing controversial claims surrounding Harry and his wife Meghan Markle's exit as senior royals.

The programme had an interview with Omid Scobie, co-author of Harry and Meghan's biography "Finding Freedom," who claimed that insiders from royal households fed negative stories about the couple during their departure. The journalist said, "There were some people who felt she [Meghan] needed to be put in her place. I think by leaking a negative story, that's punishment. There's been rumours for quite some time that a lot of the most damaging and negative stories... have come from other royal households or from other royal aides. From my own research and reporting that's exactly true."

The documentary also featured an appearance from Jenny Afia, a lawyer from Schillings who represents Meghan, who was speaking with the Duchess' permission and insisting that the bullying claims printed about her were "false," reports Mail Online.

Meanwhile, it featured royal experts defending the royal family and arguing that people "behind the scenes" had only come forward to the press after "getting annoyed" at the behaviour of the Duke and the Duchess of Sussex.

However, the royal family maintains that they never fed such stories in the first place, and adopted the "mantra of a period of silence" even when the Sussexes made damaging claims about the palace in their tell-all interview with Oprah Winfrey earlier this year.

The three royal households, which had already expressed disappointments at not being offered a proper right to reply in the documentary, said in a fresh statement, "A free, responsible and open Press is of vital importance to a healthy democracy. However, too often overblown and unfounded claims from unnamed sources are presented as facts and it is disappointing when anyone, including the BBC, gives them credibility."

British Royal Family
British Royal Family Photo: AFP / Tolga AKMEN