The writer, who is co-creator and an executive producer on the show, warned in a since-deleted blog post "there are larger and more toxic butterflies to come".

Martin had previously said he would share "everything that's gone wrong" with the adaptation of HBO's House Of The Dragon, which is partly based on his book Fire & Blood and is the prequel to the hit series, Game Of Thrones.

In the lengthy blog post, he described a disagreement about removing a character, Prince Maelor, from the plot - insisting it has larger repercussions for series three and four.

He said: "The prince's birth was no longer just going to be pushed back to series three. He was never going to be born at all. The younger son of Aegon and Helaena would never appear."

Martin said there were practical reasons against casting another child, including the cost.

But he said showrunner Ryan Condal previously "assured me that we were not losing Prince Maelor, simply postponing him" after the author had initially "argued against" dropping the character from the second series.

In a statement reported by showbiz news website Deadline, HBO defended Mr Condal: "Commonly, when adapting a book for the screen, with its own format and limitations, the showrunner ultimately is required to make difficult choices about the characters and stories the audience will follow.

"We believe that Ryan Condal and his team have done an extraordinary job and the millions of fans the series has amassed over the first two series will continue to enjoy it."

Martin went on to compare the HBO series with Fire & Blood, which the show is based on.

He said his book features Aegon and Helaena Targaryen - played by Tom Glynn-Carney and Phia Saban, respectively - who have twins Jaehaera and Jaehaerys along with a younger son, Maelor.

But he said in the show the couple only have the twins.

He said: "Maelor is a two-year-old toddler in Fire & Blood, but like our butterfly he has an impact on the story all out of proportion to his size."

He argued the changes "may make sense in terms of budgets and shooting schedules. But simpler is not better".

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On a recent episode of HBO's official House Of The Dragon podcast, Mr Condal explained "we had to make some compromises in rendering the story" when it came to eliminating the Maelor character.

"It did have a ripple effect, and we decided that we were going to lean into it and try to make it a strength, instead of playing it as a weakness."

Meanwhile, George RR Martin's blog post also described how the original story in his book progresses [we are avoiding any spoilers], speculates on the show's character and plot development, and finally ends on a cryptic note.

"There are larger and more toxic butterflies to come, if HOUSE OF THE DRAGON goes ahead with some of the changes being contemplated for series three and four," he said.