Actress Emilia Clarke and author George RR Martin have confirmed that a Game of Thrones spin-off series based around Jon Snow, a character portrayed by actor Kit Harington, is being developed at HBO.

It was reported last week that HBO has started working on the spin-off show that would take place after the events of Game of Thrones with Harington reprising Jon Snow’s role.

Clarke, who played Daenerys Targaryen during the original show’s run from 2011 to 2019, told BBC in an interview that Harington told her about the new series.

“He has told me about it. And I know it exists. It’s happening. It’s been created by Kit as far as I can understand, so he’s in it from the ground up. So, what you will be watching, hopefully, if it happens, is certified by Kit Harington,” Clarke said.

However, the actor ruled out the possibility of her returning as Daenerys Targaryen in the spin-off.

Martin, whose A Song of Ice and Fire book series is the source material for Game of Thrones, revealed that the project’s working title is Snow and also said that it was Harrington “who brought the idea” to them.

“I cannot tell you the names of the writers/ showrunners since that has not been cleared for release yet but Kit brought them in too, his own team, and they are terrific,” the author wrote on his blog.

Martin added that he is “involved” in the series, similarly to other spin-off shows like The Hedge Knight, The Sea Snake and Ten Thousand Ships.

“Kit’s team visited me here in Santa Fe and worked with me and my own team of brilliant, talented writers/consultants to hammer out the show,” Martin wrote.

All the four spin-off shows are still in the “script stage” and are yet to be officially greenlit by HBO, he added.

“Nothing has been green lit yet, and there is no guarantee when or if it will be on any of these shows. The likelihood of all four series getting on the air well, I'd love it, but that’s not the way it works, usually. Snow has been in development almost as long as the other three, but for whatever reason, it was never announced and it never leaked until now,” he said.

HBO will soon be coming out with its first Game of Thrones spin-off, the prequel titled House of the Dragon, which is scheduled to premiere on August 21.