Prince Harry and his wife Meghan will begin their new life outside the royal inner circle at the start of April, their spokeswoman said Wednesday, as Buckingham Palace said it was reviewing the couple's use of the "Sussex Royal" label.

The couple will formally step down as senior royals from March 31, the spokeswoman said, and will no longer carry out duties on behalf of Queen Elizabeth II after that date.

They will no longer have an office at Buckingham Palace -- the queen's London residence -- and will instead be represented through their British charity from April 1, she added.

Harry, the 35-year-old second son of the heir apparent Prince Charles, will remain sixth in line to the throne, with no change in the line of succession.

The former army officer will also keep his military ranks of major, lieutenant commander and squadron leader in the army, navy and air force, the spokeswoman announced.

He and Meghan, 38, will continue to be known as the Duke and Duchess of Sussex, as well as the Earl and Countess of Dumbarton in Scotland, and Baron and Baroness Kilkeel in Northern Ireland.

Harry and US former actress Meghan stunned the family last month by announcing that they wanted to step back from front-line royal duties.

The couple cited wanting financial independence as one factor in their decision.

Harry and Meghan
Prince Harry and Meghan Markle are pictured here. POOL/Jeremy Selwyn

But they could be dealt a blow after it was reported that the queen could ban them from using the "Sussex Royal" brand.

The couple use the name for their popular Instagram account and a website set up after their shock announcement. They also have made dozens of trademark applications for various products.

But future use of the name "needed to be reviewed" and talks were continuing, an unnamed royal source was quoted as saying by Britain's domestic Press Association news agency.

"As the Duke and Duchess of Sussex are stepping back as senior members of the royal family and will work towards financial independence, use of the word 'royal', in this context, needed to be reviewed," the source said.

The Daily Mail newspaper reported on Wednesday that senior officials had already agreed it was no longer "tenable" for the couple to keep the word "royal" in their branding.

Harry and Meghan have been living in a luxury mansion on Canada's Pacific west coast with their baby son Archie since the New Year.

Meanwhile, the National Theatre -- of which Meghan is a patron -- denied claims it was angered by the couple's decision to move to Canada.

Its artistic director Rufus Norris told The Daily Telegraph newspaper that Meghan's patronage was expected to be "business as usual" and reports to the contrary were "a complete fiction".

Harry and Meghan first used the Sussex Royal name when they created their own household following a split from brother Prince William.

Harry said in October that he and his brother were on "different paths".