Security before the premiere of the film "The Interview" in Los Angeles, California on December 11, 2014 © AFP/File

Washington (AFP) - Cyber attacks that ultimately prompted Sony Pictures to scrap the release of a madcap comedy about North Korea are a "serious national security matter," the White House said Thursday.

"The president considers this to be a serious national security matter," White House spokesman Josh Earnest said about the cyber attack on the movie giant, which US investigators have reportedly blamed on North Korea.