Naomi Watts-led Game of Thrones prequel axed by HBO

Naomi Watts was supposed to lead the new GoT prequel which has now been axed. Photo / AP

HBO's untitled Game of Thrones prequel starring Naomi Watts has been canned.

The prequel, tipped to focus on the "Age of Heroes" and the first ever battle between man and White Walker, filmed a pilot recently but will not be advancing to a series.

According to The Hollywood Reporter, writer Jane Goldman emailed the cast to share the news. THR reports HBO "as it typically does on projects in development", declined to comment.

The cancellation comes after news that HBO is nearing a deal to produce a second pilot based in the Thrones universe.

This new series is said to focus on the reign of Targaryen kings, prior to the events of Thrones but linking the two stories more closely than the now scrapped series would've done.

According to THR, the axing isn't completely out of left field as the original pilot for Thrones was reshot, recast and redeveloped before it made it to series.

This time though, sources say HBO asked for changes in edits but eventually scrapped the entire thing.

The axed prequel was also set to feature Miranda Richardson, Joshua Whitehouse, Marquis Rodrigez and more.

The pilot pass comes just after Game of Thrones showrunners David Benioff and Dan Weiss were forced to quit their gig writing a planned trilogy of Star Wars feature films.

The duo are instead focusing on a five-year, $250 million film and TV deal with Netflix.