Unseen chapter from Game of Thrones book released

Game of Thrones season four starts on April 7.

Game of Thrones creator George R.R. Martin has released an excerpt from the impending sixth installment of A Song of Ice and Fire series.

The chapter, named Mercy, was posted on Martin's website - which has been overwhelmed since it went live.

The author announced the sneak preview on his blog, saying the except was actually an "old chapter", but it had never been published.

"It's old in that it was written a long time ago, predating any of the samples that you have seen," Martin wrote. "The first draft was, at any rate. I've rewritten it a dozen times since then."

The chapter is from The Winds of Winter, which is the second-to-last book in the series that inspired the hit television show.

The last installment, A Dance with Dragon was published in 2011, a time lag that has caused concerns over the pacing of the television show. There is still no word on a release date for The Winds of Winter.

Season four of Game of Thrones premieres on April 7.