A German royal has warned Prince Harry to be "more careful" after "embarrassing" the King and Queen.
The Duke of Sussex took a selfie with a so-called "fake prince" at John Travolta's Living Legends of Aviation gala.
Prince Alexander Schaumburg-Lippe warned Harry, 39, to show "more caution" after he posed with his distant relative at the awards bash.
Prince Harry beamed as he posed with Mario-Max Schaumburg-Lippe at the black tie event hosted at the Beverly Hills Hilton in LA on Friday night.
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|Prince Harry 'embarrassed' the King and Queen, according to a German prince
However, the German has since been branded a "fake prince".
Prince Alexander said: "I hope [Harry] will be more careful in the future and also always keep in mind the dignity of their majesties the King and Queen."
Mario-Max became known after appearing on Germany's Big Brother and several reality shows in the US.
Prince Alexander continued to tell The Mail: "If Prince Harry read about these things he may exercise more caution in the future, which would be a wise thing to do.
Instagram / Prince Mario Max
|Mario-Max Schaumburg-Lippe posted this selfie with the duke on Instagram
"In his position, you can't surround yourself with people without vetting them first."
Mario-Max was adopted at the age of 24 by a member of the Schaumburg-Lippe family and subsequently took on the title of prince.
However, Prince Alexander has asserted that Mario-Max is not a prince and has been "harvesting our name" for fame.
Mario-Max later shared his birth certificate on social media after his family questioned his right to use the title of prince.
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|Prince Alexander Schaumburg-Lippe has warned Prince Harry about posing with a 'fake prince'
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Instagram / Lauren Sanchez | Prince Harry posed with John Travolta, Lauren Sanchez, and Jeff Bezos at the glitzy LA bash
Writing in German and English, he said he is "Prince Waldemar, son of Princess Feodora of Denmark, and Princess Antonia Schaumburg-Lippe".
His social media supporters supported him, with one posting on X: "You are a gentleman, sir. Ignore these people. They have no honour."
During the glitzy ceremony in LA, the duke also posed with John Travolta, Jeff Bezos and the latter's fiancée Lauren Sanchez.