Prince William on Thursday defended the British royal family after his younger brother Harry and wife Meghan accused them of racism in a bombshell interview watched around the world.

"We're very much not a racist family," William told reporters during a visit to a multi-racial school in a deprived area of east London.

The Duke of Cambridge, as he is formally known, is the first senior royal to speak out publicly about the explosive row that has engulfed Britain's most famous family.

William, 38, said he had yet to speak to Harry, 36, since the interview with US chat show host Oprah Winfrey first aired in the United States on Sunday night.

Harry and his mixed-race spouse Meghan moved to California with their young son Archie last year after their shock announcement to step down as working royals.

"No, I haven't spoken to him yet, but I will do," William said.

Harry told Winfrey there was "space" between the brothers, who had been close since the death of their mother princess Diana in 1997, after reports of a rift since he married Meghan.

A keenly awaited statement from Queen Elizabeth II, 94, was issued Tuesday and was conciliatory towards Harry and Meghan.

But it also stressed that "some recollections may vary", as Buckingham Palace vowed to look into the couple's assertion that an unidentified royal had asked how dark their unborn son's skin would be.

Harry and William's father, the queen's oldest son and heir Prince Charles, has yet to comment on the controversy.

On Tuesday, he toured a Nigerian Christian church in London whose pastors are promoting a drive to vaccinate more black people against the coronavirus.

During the interview, Harry said his father, 72, stopped taking his calls after his move to North America, but they were trying to rebuild bridges.

He also said that Charles and his brother, who is second in line to the throne, were "trapped" in a hidebound institution.

Britain's Prince William  and his wife Kate visited a multiracial school in London
Britain's Prince William and his wife Kate visited a multiracial school in London POOL / JUSTIN TALLIS

Meghan said she struggled to adapt to royal life after the couple's fairytale wedding in 2018, even to the extent of suicidal thoughts.

But she said she was not given any support by royal officials.

William and his wife Kate are increasingly involved in promoting mental health support, particularly through the coronavirus pandemic.

Meghan complained to British broadcaster ITV after breakfast television host Piers Morgan launched a furious tirade about the interview and said he did not believe her claims about racism and mental health struggles.

William and Kate's visit to School 21 in Stratford, east London, on Thursday was to mark the return of children to classes after two months of coronavirus lockdown that forced lessons online.

They are also rolling out to secondary schools a mental health project that Kate launched in primary schools three years ago.

The queen has said Harry and Meghan's allegations will be addressed in private, lowering expectations of any public statement about the conclusions.

The whole affair has plunged the monarchy into crisis and is being keenly watched around the world. The queen is also head of state in 15 mainly non-white, Commonwealth countries.

One newspaper commentator called the allegations a "soft-power disaster for Britain", given the royal family's global brand.

It has also opened the door for republicans to make a fresh push for support to remove the queen as head of state, although public backing for the institution at home remains strong.

There have been repercussions, too, in the media, which Harry and Meghan accused of racially biased, unfavourable coverage, with renewed calls for newsrooms to be made more representative.

Morgan quit after he refused a demand by ITV bosses to apologise, while the head of the Society of Editors guild of senior journalists stepped down after rejecting charges of media racism.

More than 250 journalists wrote in an open letter that the refusal to accept bigotry in the media was "laughable" and showed an industry "in denial".