The royal households have issued a rare joint statement criticising the BBC for giving credibility to “overblown and unfounded claims” in a new documentary about William and Harry’s relationship with the media.

Airing on Monday, the first episode of the two-part The Princes And The Press programme, presented by Amol Rajan, included suggestions of royal sources speaking to journalists behind the scenes.

The show was billed as telling the story “of one of the most dramatic periods in modern royal history” and how William and Harry‘s relationship with the media changed following the Queen’s Diamond Jubilee in 2012.

In response, Buckingham Palace, Clarence House and Kensington Palace gave a joint statement to the BBC, which was shown at the end of the programme.

“A free, responsible and open press is of vital importance to a healthy democracy,” the statement said. “However, too often it is overblown and unfounded claims from unnamed sources that are presented as facts and it is disappointing when anyone, including the BBC, gives them credibility.”

During the programme, a lawyer for Meghan also responded to 2018 reports on her alleged treatment of palace staff.

In March, Buckingham Palace said it was investigating claims of bullying after The Times newspaper reported that the duchess allegedly drove out two personal assistants and “humiliated” staff on several occasions, which she denies.

Jenny Afia, from the law firm Schillings, told Rajan in the documentary: “Those stories were false. This narrative that no one can work for the Duchess of Sussex, she was too difficult and demanding as a boss and everyone had to leave, it’s just not true.”

Elsewhere in the programme, a private investigator apologised for targeting the phone of Prince Harry’s ex-girlfriend and admitted he helped “rob” the duke of his teenage years.

Gavin Burrows said there had been a “ruthless” culture in parts of the media during the early 2000s, when he said Chelsy Davy’s phone had been under surveillance.

Mr Burrows told the documentary there was much greater interest in the Duke of Sussex than his brother when he began working for the now defunct News Of The World in 2000, and that editors had told him that “Harry had basically become the new Diana”.

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Following the airing of the programme, a report published in The Sun claimed that William had banned aides from briefing against family members.

According to the newspaper, the duke was “clear” he did not want aides to say anything about the other households after he saw reports during the split of his parents.

The second part of the documentary, which will examine the period from 2018 to 2021, is due to air on Monday 29 November.