Kate Middleton conspiracy theories that ran wild across social media platforms were amplified by Russian propagandists, who used them to promote their own agenda, researchers have suggested.

Before Middleton announced her cancer diagnosis on March 22, various speculations about the Princess of Wales' health and whereabouts ran rampant on TikTok, X, and other platforms, including claims that she was in a coma or had died following her abdominal surgery in January.

Security researchers at Cardiff University in Wales found that a Russian disinformation campaign allegedly capitalized on "#KateGate" and exploited the conspiracy theories about Middleton to spread pro-Russian and anti-Ukrainian narratives.

Cardiff University's Security, Crime and Intelligence Institute director Martin Innes told ABC Australia radio host Patricia Karvelas that he and his team monitored traffic around the story about Middleton as part of their "long-term program of research looking at disinformation and information manipulation online."

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Kate Middleton Britain's Catherine, Princess of Wales
Britain's Catherine, Princess of Wales smiles as she arrives to attend the Royal Variety Performance at the Royal Albert Hall in London on November 30, 2023.
(Photo : Getty Images/Daniel Leal/AFP)

According to the professor, researchers noticed "unusual spikes" in the traffic caused by "unusual patterns of activity and behavior on a number of accounts."

The researchers identified the accounts as belonging to the Russian disinformation group Doppelgänger, which they had previously looked into.

Innes explained that the Kremlin-linked group -- which he said was "well-known in the open-source research community" -- did not start any conspiracy theory but instead took "advantage of the massive amount of interest" in Middleton's health and whereabouts.

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Explaining their tactics, the professor said the group would look for popular posts about Middleton and reply to these posts with their own content.

"Typically, the content would either be denigrating Ukraine and celebrating Russia's achievements in the war or talking up the integrity of the recent Russian election," Innes said.

The group is able to get "a lot of eyeballs" on their messages by inserting them in popular posts or seizing on trending hashtags, the expert explained.

Replying to posts rather than posting original content made it more difficult for social media platforms to regulate the group's comments, according to Innes.

Prince William, Kate Middleton, Princess Charlotte, Prince George, Prince Louis
Revd Paul Williams (L) stands bay as Prince William (C) and Princess Charlotte (2L), Catherine, Princess of Wales (R) walks away from the church with Prince George and Prince Louis after attending the Royal Family's traditional Christmas Day service at St Mary Magdalene Church on the Sandringham Estate in eastern England, on Dec. 25, 2023.
(Photo : Adrian Dennis/AFP via Getty Images)

Innes told NBC News that it was easy for the Russia-linked accounts to jump on the story because "it was already being framed in conspiracy terms."

Describing the group as a "dark PR firm," the security expert told ABC Australia that rather than being part of the state security services, Doppelgänger is a commercial organization allegedly hired by the Kremlin.

The group focused on "destabilization" and "undermining trust in institutions" such as government, the monarchy, and media, Innes told NBC News.

In addition to Russia, researchers also found that similar groups working out of other countries, such as Pakistan and Indonesia, also used the attention surrounding Middleton to amplify their own agendas.

Middleton put an end to the conspiracy theories last week when she released a video in which she revealed that she is undergoing "preventative chemotherapy" after cancer was found in her system following her surgery.

The Princess of Wales also subtly addressed her nearly three-month absence from the public eye.

"It has taken me time to recover from major surgery in order to start my treatment," she said.

"But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK," Middleton added.

The royal assured the public that she is "well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits."

Following her announcement, Middleton skipped the annual Easter church service Sunday, along with her husband Prince William and their children, Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5.