The Duke of Sussex and the Duke of Cambridge have denied a “false story” in a UK newspaper speculating about their relationship.
A statement on behalf of Princes Harry and William described the story’s “inflammatory language” as “offensive”.
It comes after a source told the Times the Sussexes felt they had been pushed out by William’s “bullying attitude”.
The brothers are to meet the Queen and Prince of Wales later to discuss Harry and Meghan’s future.
The couple want to step back as senior members of the Royal Family, while also becoming financially independent.
A statement on behalf of Harry and William said: “Despite clear denials, a false story ran in a UK newspaper today speculating about the relationship between the Duke of Sussex and the Duke of Cambridge.
“For brothers who care so deeply about the issues surrounding mental health, the use of inflammatory language in this way is offensive and potentially harmful.”
Claims of bullying have been strongly contested by other sources close to the Cambridges and Harry, the Times article reported.
In October, Harry responded to speculation about a rift between the brothers by saying the pair were “on different paths at the moment” but he loved William “dearly”.
Meghan is expected to join the discussion by phone from Canada.
It is hoped the talks will produce a “next step” on the way to defining the couple’s new relationship with the Royal Family – in line with the Queen’s wish to find a solution within days.
However, our correspondent said a deal “might take time” to be agreed and implemented.
Among the issues likely to be discussed are what funding the duke and duchess will receive, whether they will keep their titles and what royal duties they will continue to carry out.
The Queen, Prince Charles, William and Harry are expected to review a range of possibilities for the Sussexes, taking into account plans outlined by the couple.
The final arrangement could provide a blueprint for future royal generations, including the Duke of Cambridge’s younger children Princess Charlotte and Prince Louis.
Monday’s gathering at the Queen’s estate in Norfolk – being described as the “Sandringham summit” – will be the first time the monarch has spoken face-to-face with Prince Harry since the Sussexes’ announcement.
Prince Charles has returned from Oman after attending a condolence ceremony following the death of Sultan Qaboos bin Said Al Said.