A Meghan Markle and Prince Harry supporter has accused Kensington Palace of "North Korea" propaganda.
It had been hoped that Princess Kate's decision to announce her cancer diagnosis via video publicly would end the online conspiracy theories.
But despite Kate's emotional video message, the outlandish claims have continued to spiral online.
Social media platforms have been urged to clamp down on the abuse.
A Meghan Markle and Prince Harry supporter has added fuel to the conspiracy theories
Getty
The CEO of X, Linda Yaccarino, posted: "A brave message delivered by Princess Kate with her signature grace.
"Her request for privacy, to protect her children and allow her to move forward (without endless speculation) seems like a reasonable request to respect."
As well as attacks towards Kate, Prince William was targeted for not sitting beside his wife in the video.
Fuelling the fire within 30 minutes of the broadcast, Christopher Bouzy, an avid supporter of Harry and Meghan, accused the Palace of "North Korea" style propaganda.
Christopher Bouzy appeared in Harry and Meghan's Netflix docuseries
Netflix
He wrote: "I am sorry to hear Kate has cancer, I hope she has a full recovery.
"But it is also clear that all three earlier photos of her were fake, and the palace tried to cover it up."
Bouzy, who appeared on the Sussexes' Netflix show, was referencing Kate's Mother's Day photo, a video of her shopping in Windsor and an image of her being driven in a car.
He added: 'The palace lied, and the British Press happily helped them lie.
Conspiracy theories have emerged about the health of Princess KateGettyLATEST ROYAL NEWS
Kate recorded a video to announce her cancer diagnosisPA"The countless 'conspiracy theory' headlines, while knowing a lot of what was being said was true.
"This is really some North Korea/Trumpian type of propaganda."
He went on to accuse Prince William of throwing his wife "under the bus" over the altered Mother's Day portrait.
Several celebrities, including Owen Jones and Blake Lively, have issued apologies to the Princess of Wales for peddling conspiracy theories about the royal.