King Charles III’s health is worrying friends and the palace as he continues to battle an undisclosed type of cancer.

“Speaking to friends of the king in recent weeks about his health, the most common response is … ‘It’s not good,’” Tom Sykes of the Daily Beast reported Thursday.

A friend of the monarch claimed Charles “is determined to beat it and they are throwing everything at it,” adding, “Everyone is staying optimistic, but he is really very unwell. More than they are letting on.”

Royal scribe Tina Brown also hinted at the monarch’s health struggles, writing recently that Charles’ cancer has put Prince William and Kate Middleton “in frightening proximity to ascending the throne just when they had hoped for a span of years to parent their children out of the public eye.”

“The prospect of it, I am told, is causing them intense anxiety.”

Sykes also reported that the king’s funeral plans — codenamed “Operation Menai Bridge” — are currently being reviewed.

A separate document that states what went well at Queen Elizabeth’s September 2022 funeral and what could be done better the next time a monarch dies is also circulating, according to the Daily Beast.