US TV talk show host Stephen Colbert is the latest celebrity to walk back comments about the Princess of Wales after her shock cancer diagnosis.

It came amid backlash at celebrities who joined in the rush of conspiracy theories following Kate’s absence after her abdominal surgery in January.

“We do a lot of shows. I tell a lot of jokes. I tell jokes about a lot of different things, mostly about what everybody is talking about,” Colbert said on Wednesday (US time).

“For the last six weeks to two months, everybody has been talking about the mystery of Kate Middleton’s disappearance from public life. Two weeks ago, we did some jokes about that mystery.”

The Late Show host admitted that he had “upset some people…even before her diagnosis was revealed” – although he stopped short of an apology to the princess.

“I can understand that a lot of my jokes have upset people in the past and some of my jokes will upset people in the future. But there’s a standard that I try to hold myself to, and that is I do not make light of somebody else’s tragedy,”  Colbert said.

It followed a monologue on The Late Show on March 17, in which Colbert said part of the online frenzy about the princess was due to people trying to insinuate her disappearance from the public eye was because of problems in her marriage to the Prince of Wales.

“The kingdom has been all aflutter by the seeming disappearance of Kate Middleton,” Colbert said at the time.

“Well now, internet sleuths are guessing that Kate’s absence may be related to her husband and the future King of England, William, having an affair.”

Kate announced her cancer diagnosis in a personal video message released on March 22. Since then, many celebrities have expressed regret at making jokes or publicly buying into some of the wilder theories about the absent princess.

Actress Blake Lively, who mocked Kate’s “Photoshop fails” in a social media post before the diagnosis was revealed, posted an apology on Instagram.

“Oh man, that post has me mortified today. I’m sorry,”  she said in the hours after Kate’s video was released.

Meanwhile reality star Kim Kardashian remains under pressure to make her own apology after she posted a picture of herself standing next to a luxury car with the caption “On my way to find Kate”.

“After the news of her having cancer has been revealed, you should really take this down. It’s extremely insensitive and you owe our princess an apology,” one comment on Kardashian’s post reads.

“Can you please go find an apology instead??” wrote another.

Meanwhile, Kate, William and their three children are believed to be bunkered down at their country estate, Anmer Hall, on the King’s Sandringham estate. They arrived in Norfolk at the weekend and are expected to spend George, Charlotte and Louis’s Easter school holidays there.

The Waleses will officially be absent from Sunday’s Easter church service at Windsor.

Buckingham Palace confirmed that the King, who is also being treated for cancer, will attend along with other members of the royal family. It will be his first public appearance at a traditional royal event since his own cancer diagnosis was revealed in January.