Britain's Prince William and Prince Harry pose with Aimon Srivaddhanaprabha, after they played in the Khun Vichai Srivaddhanaprabha Memorial Polo Trophy, at the Royal Charity Polo Day at Billingbear Polo Club, Wokingham, England, Wednesday, July 10, 2019. Picture: AP

A royal insider has claimed that the relationship between Prince Harry and Prince William has "irreparably changed".

The 35-year-old royal - who married the Duchess of Sussex in May 2018 - and his 37-year-old brother have historically shared a close relationship, but their dynamic has evolved markedly over recent months, according to the BBC.

The royals are said to have significantly different attitudes in regards to their dealings with the media, with Prince Harry eager to maintain his privacy, whilst Prince William sees communication as a key part of his role.

What's more, it's been claimed that following the decision to establish separate diary and communications staff, it's become inevitable that relations between the brothers will "sour further" over the coming months and years.

Earlier this month, it was reported that Prince William is "extremely concerned" about the Duke and Duchess of Sussex.

But despite their supposed differences, the British royal remains determined to support his younger brother through the tough times in his life.

The insider explained: "William is extremely concerned about Harry and Meghan.

"Even though the brothers have grown apart, William still cares about Harry and is hoping that he'll open up to him about his current struggles.

"William wants to be there for Harry and hates seeing him in such a bad place. Despite their differences, blood is thicker than water."

Meanwhile, Prince Harry recently confessed that he and his brother have "good days and bad days".

The royal - who has a five-month-old son called Archie with his wife - played down rumours of a rift between the siblings, insisting they will "always be there" for each other.

He shared: "We are brothers. We will always be brothers. We are certainly on different paths at the moment but I will always be there for him as I know he will always be there for me.

"We don't see each other as much as we used to because we are so busy but I love him dearly. The majority of the stuff is created out of nothing but as brothers, you know, you have good days, you have bad days."