Fans will be waiting at least another year for The Winds of Winter, the sixth book in Martin’s bestselling A Song of Ice and Fire series.

Matt Sayles/Invision / AP Matt Sayles

George RR Martin's publisher has confirmed that The Winds of Winter, the upcoming sixth book in the popular A Song of Ice and Fire series, is not scheduled for publication in 2015.

"I have no information on likely delivery," HarperCollins's Jane Johnson told The Guardian . "These are increasingly complex books and require immense amounts of concentration to write. Fans really ought to appreciate that the length of these monsters is equivalent to two or three novels by other writers." The fifth book in the series, A Dance With Dragons, was published in 2011.

In December, a "12 Days of Christmas" promotion for Martin's books led many fans to believe that an announcement about The Winds of Winter was imminent, prompting the author to quash the rumors in a post on his blog.

"Somehow, from somewhere, the rumor arose that the "12 Days" were actually a countdown... not to Xmas, but to the publication of THE WINDS OF WINTER, or the announcement of its completion and/ or pub date," Martin wrote. "Sorry. Not true."

"Look, I've said before, and I will say again, I don't play games with news about the books," he explained. "I know how many people are waiting, how long they have been waiting, how anxious they are. I am still working on WINDS. When it's done, I will announce it here. There won't be any clues to decipher, any codes or hidden meanings, the announcement will be straightforward and to the point. I won't time it to coincide with Xmas or Valentine's Day or Lincoln's Birthday, the book will not rise from the dead with Jesus on Easter Sunday. When it is done, I will say that's it is done [sic], on whatever day I happen to finish."

Although there will be no update to the series in 2015, an illustrated compilation of three previously-published prequel novellas set in Westeros will be released in October. The collection, titled A Knight of the Seven Kingdoms have not been published together before, and Martin's publisher hinted that fans will pick up clues about future developments in Westeros as they read them.

The A Song of Ice and Fire series has been adapted for television as HBO's immensely popular Game of Thrones, now in its 5th season.