Sunday's premiere of season four of the fantasy epic drew the US TV Network's biggest audience for seven years.

The series is based on the bestselling fantasy book series by George R.R. Martinabout and is about civil war, nobility, mythical creatures and treachery set on the continent of Westeros.

The first episode of series 4 was seen by an average of 6.6 million viewers, making it HBO’s most-watched program since the finale of “The Sopranos” in 2007 (11.9 million viewers).

Game of Thrones is a phenomenon like no other,' Michael Lombardo, president of HBO Programming said in a statement yesterday.

'David Benioff and D.B. Weiss, along with their talented collaborators, continue to surpass themselves, and we look forward to more of their dazzling storytelling.'

The series has received high praise in the US, with the Los Angeles Times calling it “the Best Television Show Ever” while another publication, Newsday, hailed the series as “still TV’s best”.