The Duke of Edinburgh, who died last Friday, will be buried on Saturday at Windsor Castle, west of London, with just 30 mourners, most of them close family.

Queen Elizabeth II is understood to have decided that all the royals will wear civilian clothing, The Sun tabloid and other media reported.

The funeral would otherwise have emphasised former British Army captain Prince Harry's loss of honorary military titles after his shock departure from royal life last year.

Harry, the Duke of Sussex, was stripped of his military titles after stepping away from senior royal duties and moving to California with his wife, Meghan.

While Harry -- the Queen's grandson -- did two tours of duty in Afghanistan, he is only allowed to wear a suit with service medals.

Another potential row comes in the shape of the monarch's second son Prince Andrew, a former Royal Navy helicopter pilot who saw action in the 1982 Falklands War.

He has been sidelined from public duties because of outrage at his defence of his friendship with the convicted sex offender Jeffrey Epstein.

He was set to take the honorary rank of admiral for his 60th birthday but the appointment was put on hold.

The Sun said there would have been "serious displeasure" in the Navy had he gone ahead with the uniform plan.

The Daily Telegraph reported that royals had held "intense discussions" to allay concerns about embarrassing the family if Andrew and Harry -- the only royals to have seen frontline service -- were not wearing uniform.

The broadsheet reported that the decision ultimately lay with the Queen, while The Sun cited insiders as saying she "personally stepped in" to suggest the civilian clothing rule.

The decision would see the royal family present a united front, at least sartorially, while the funeral will have a strong military element due to Prince Philip's past as a naval commander.

Harry's appearance at the funeral will be the first time he has been seen in public with the royals since he and Meghan gave an explosive television interview broadcast last month accusing unnamed royals of racism.