A second cryptic teaser to the fifth season of HBO's flagship 'Game of Thrones' has been released online.

AS Game of Thrones fans gear up for its fifth season, author George R.R. Martin has revealed some bad news about it — and “everybody better be on their toes”.

Martin has revealed that some people will die in the upcoming TV series, which could upset those who follow his famous fantasy novels.

Martin told Showbiz411.com: “People are going to die who don’t die in the books, so even the book readers will be unhappy. So everybody better be on their toes. David and D.B. (David Benioff and D.B. Weiss co-creators of ‘Game Of Thrones) are even bloodier than I am.”

Martin, who was speaking at the Writers Guild West Awards, also said he was unsure of how many more seasons the show had to go in the future.

ESCAPE: Game of Thrones tours in Croatia

MORE: The worst part of being a Game of Thrones star

WHY: Game of Thrones new costumes have nipples

When asked what he knew, he said: “ Not really certain yet. This is the fifth season, the sixth season HBO picked up last year. We will have a 7th, 8th or 9th, no one knows. They only renew one or two seasons at a time. After we do season 6, maybe we’ll get a renewal for 7th and 8th. That all depends, Television is a very changeable medium.”

But no matter what happens, Martin said he would finish the book series with two more novels, making it seven books in total.

“ ... whatever happens with the show I’m going to finish the books, it will be seven books. But each of these books are 1500 pages long and they each have enough material in them for several seasons. I have two more books, the one I’m writing right now, ‘The Winds Of Winter,’ and after that the last book, ‘The Dream of Spring,’ so those will be the two final books. But we’re talking 3000 pages of material. How many seasons that translates too? That’s up to D.B. And David.”

Fans of the TV show and book series recently saw another trailer to season five of the smash hit HBO series.

It opens with Brienne intoning: “Nothing is more hateful than failing to protect the one you love.”

Littlefinger promises more cruel and devious behaviour as we see him telling Sansa: “There’s no justice in this world. Not unless we make it. Avenge them.”

Most thrillingly of all, master manipulator Lord Varys offers some insight on the future of the throne.

“You could help another climb those steps and take that seat,” he tells Tyrion. “The Seven Kingdoms needs a ruler loved by millions with a powerful army and the right family name.”

“Good luck finding him,” says Tyrion.

“Who said anything about him?” replies Varys.

He could mean that the throne should go to Danyerys, who is seen warning: “I’m not going to stop the wheel, I’m going to break the wheel.”

Set to the theme of Heroes by David Bowie, the trailer has caused enormous excitement among the show’s devoted fans.