A few US celebrities weighed in with jokes amid the surge in online speculation, including by the social media star Kim Kardashian, who published a series of photos to her 364 million followers on Instagram with the caption: “On my way to find Kate.”

The post, which at the time of writing is still on her page, received an immediate backlash after the Princess announced in a personal video message on Friday that she has been undergoing preventative chemotherapy since late February.

“How do you feel now it’s been announced she has cancer?” one follower asked on Kardashian’s post, with another weighing in writing: “This didn’t age well. You never know what someone is battling.”

The Princess’s revelation sparked an outpouring of support and well wishes from around the world and has prompted a fierce outcry at some of the nasty conspiracy theories propagated during her absence from public life.

On Saturday, Hollywood star Jamie Lee Curtis called for people to stop peddling conspiracy theories about the Princess, saying: “Can we please just STOP with this bull—t conspiracy theory? This is a human being with young children, and clearly some sort of health issue.

“That is a private matter. Do we not have better things to do and more important things to think about and be concerned about than this? It’s a really low point in our society when there are SO MANY crucial issues that need our attention.”