No release date has been set for Martin's much-anticipated 'Winds of Winter.'

George R.R. Martin says he won't be at this year's San Diego Comic-Con.

Martin has been a mainstay of HBO's Game of Thrones panel since 2010, moderating his first three years and then sitting as a panelist for 2013 and 2014. But in a blog post Monday, Martin announced that he needed to buckle down on the next installment in the Song of Ice and Fire series, the long-awaited Winds of Winter.

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Martin began the blog post by apologizing to fans who had planned to see him at November's World Fantasy Convention in Saratoga, New York.

"I have too much to do. Too many things on my plate. Son of Kong foremost amongst them," Martin wrote. Son of Kong is an inside joke Martin uses to refer to Winds of Winter on his blog.

"Also, I have decided against attending this year's San Diego Comicon. Same reason. But since Comicon was never listed on my Appearances page, scratching it is not as big a deal," Martin continued.

Late last year, Martin's rep told The Hollywood Reporter the author was cutting down on appearances to focus on writing. That followed a year that had included a busy slate of media stops including Conan, Last Week Tonight and Late Night.

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Fans have bemoaned the long wait between Martin's books, with the previous installment, A Dance With Dragons, being released in 2010. Martin has already said the HBO series will likely outpace his books, while his U.K. publisher HarperCollins told fans not to expect Winds of Winter this year.

"George is indeed focusing on his writing, and will therefore not be attending SDCC this year. Since he never confirmed that he would attend in 2015, this really doesn’t affect any plans," a spokesperson for Penguin Random House, Martin's U.S. publisher, told THR.

Martin adds a caveat about his trimmed slate of appearances: "Should I complete and deliver WINDS OF WINTER before these cons roll round, I reserve the right to change my mind."

Game of Thrones returns with season five April 12 on HBO.

San Diego Comic-Con did not immediately respond to a request for comment. HBO declined to comment.

Email: Aaron.Couch@THR.com

Twitter: @AaronCouch