Epic medieval-fantasy drama series "Game of Thrones" will return for a fourth season, US cable channel HBO confirmed.

The critically acclaimed show -- which chronicles the myriad power struggles in the fictional continents of Westeros and Essos -- returned for its third season on March 31.

HBO spokesman Quentin Schaffer told AFP the series would likely begin filming later this year, which would put it on course for a release date in 2014.

"We are picking it up for 10 episodes. It will likely be back in production this summer," Schaffer said.

Based on "A Song of Ice and Fire", the series of fantasy novels by George R.R. Martin, "Game of Thrones" has become one of the most talked-about series on US television since its debut in 2011.

The first episode of the third season broadcast in the US on Sunday attracted 4.4 million viewers, making it the most-watched episode in the series' short history.

The show has also become the most pirated television series in the world. According to website Torrentfreak, the final episode of the second series in 2012 was illegally downloaded by some 4.3 million people.

"I probably shouldn't be saying this, but it is a compliment of sorts," HBO director of programming Michael Lombardo said in a recent interview.

"The demand is there. And it certainly didn't negatively impact the DVD sales. (Piracy is) something that comes along with having a wildly successful show on a subscription network."

Source: AFP