The Duke of York, 63, is said to be kept in the dark over whether he can wear the grand velvet get-up and insignia showing his position as a Knight of the Garter.
According to a Royal source, Charles, 74, is torn following his disgraced brother’s 2019 scandal.
It comes after Andrew was forced to take a step back from his duties after claims he had sex with Virginia Giuffre.
An insider has now said the shamed family member feels “disrespected” over being told what to wear.
They told the Mirror: “Andrew is furious.
“He’s already not playing a part and now he feels he is being disrespected and dictated to over something he is fully entitled to [wear].”
The event on May 6 will be a “Collar Day” which means members of the Order of the Garter will wear uniform showing the knighthood they belong to.
However, Andrew could be seen in a lounge suit instead.
The source added the royals might fear backlash after he paid accuser Ms Giuffre in a £12million settlement to avoid going to court.
The prince was previously told he couldn’t wear his military uniform at the Queen‘s funeral.
He was also stripped of his military title Colonel of the Grenadier Guards.
The King’s ceremony will be scaled down compared to the Queen’s back in 1953.
It is expected to be around 90 minutes long, instead of three hours, and will represent Britain’s diverse ethnic make-up.
It’s understood Westminster Abbey will only hold 2,000 guests rather than the 8,000 it did 60 years ago.
And Charles will don military uniform instead of silk stockings and royal robes as he represents the “modern 21st century monarchy”.
Buckingham Palace has been contacted for a comment.