Celebrities who took part in the online frenzy of Kate rumours and conspiracy theories are apologising following the Princess of Wales’s cancer diagnosis.

In a moving video released on Friday, Kate revealed that she’d been undergoing chemotherapy in the wake of major abdominal surgery in January, which led to cancer cells being found in subsequent tests.

At the time, Kate’s condition was not disclosed to the public, and the release of a photoshopped image of the princess and her children exacerbated the spread of conspiracy theories speculating on the reason behind her low profile.

Actor Blake Lively was one of the first to apologise for partaking in the frenzy, referring to a now-deleted post that seemingly poked fun at Kate posting an edited picture of her family for Mother’s Day.

Posting on an Instagram Story on Friday (22 March), the Gossip Girl star wrote: “I’m sure no one cares today but I feel I have to acknowledge this.

“I made a silly post around the ‘photoshop fails’ frenzy and, oh, man, that post has me mortified today. I’m sorry.”

The Age of Adaline actor had made an Instagram post announcing an update for her alcohol brand on 15 March, when she made a subtle nod to the photoshopped family photo.

Blake Lively said she is ‘mortified’ by the ‘silly post’ she made (Getty Images for Michael Kors)

Lively’s post showed a photo of her head conspicuously photoshopped onto a distorted woman’s body lounging by a pool, with one of her Betty Buzz drinks in hand. Seemingly poking fun at rumours over Kate’s whereabouts, Lively added in the post, “Now you know why I’ve been MIA.”

Journalist and political activist Owen Jones has also expressed regret for adding to commentary on Kate’s whereabouts.

After photo agencies pulled the photoshopped family picture, Jones remarked on the “kill notice” with: “I am so obsessed with this already omg!!”

Another post featured Jones sharing his scepticism about a photograph of Kate and Prince William in a car together. He wrote: “You have to be kidding me. That is not a public appearance. Choo choo! All aboard the Kate Middleton truther express!”

However, the journalist has now said he feels “ashamed” for the speculation, and wishes Kate well.

“As someone who speculated on this without considering it could be a serious health condition, I’m very ashamed to be honest, and all the very best to her,” Jones wrote in a post on X/Twitter.

In the week before, Kensington Palace had issued a photo of Kate and her three children on Mother’s Day. In an unprecedented move, photo agencies recalled the picture after realising it had been manipulated. Kate then addressed the edited image, writing on X/Twitter: “Like many amateur photographers, I do occasionally experiment with editing.

“I wanted to express my apologies for any confusion the family photograph we shared yesterday caused.”

Meanwhile, fans have been calling on reality TV star Kim Kardashian to apologise for joining in the speculation about why Kate had been absent from public life.

Kim Kardashian posted a picture of herself stood next to a car with the caption ‘On my way to find Kate’ (Getty Images)

On 17 March_, the reality star posted a photo of herself posing in front of a luxury car, and captioned the post: “On my way to go 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 person commented on Kardashian’s post.

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

On social media, fans have also asked British-American comedian John Oliver to retract a joke made during an appearance on Watch What Happens Live with Andy Cohen.

“There is a non-zero chance she died 18 months ago,” Oliver quipped earlier this month. “They might be Weekend at Bernie’s-ing this situation. I’m not saying it happened, but I’m saying it’s non-zero until proven otherwise. Until we see her sitting there with a copy of the day’s paper.”

Weekend at Bernie’s was a 1989 comedy film in which two people manipulate a dead body to make it appear as if he’s still alive.

Piers Morgan called out Oliver for his comments on X/Twitter after the announcement that Kate is receiving cancer treatment. He said: “I hope this smug p***k has the decency to apologise for such a disgusting ‘joke’.”

At the time of writing, neither Kardashian or Oliver have responded to criticism of their comments. The Independent has contacted them for comment.

The 42-year-old princess said on Friday that she needed to recover from surgery before she could start “preventative chemotherapy”, as advised by her medical team.

“This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family,” she added.

Kate explained she had needed time to come to terms with the news and tell her children, Prince George, 10, Princess Charlotte, eight, and Prince Louis, five, before informing the wider world.

She said: “It has been an incredibly tough couple of months for our entire family, but I’ve had a fantastic medical team who have taken great care of me, for which I am so grateful.

“In January, I underwent major abdominal surgery in London and at the time, it was thought that my condition was non-cancerous.

“The surgery was successful. However, tests after the operation found cancer had been present. My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment.”

Praising her husband as “a great source of comfort and reassurance”, Kate said: “It has taken me time to recover from major surgery in order to start my treatment.

“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.

“As I have said to them, I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits.”