Psy has admitted that 'Gangnam Style' wasn't meant to get so big.

The Korean unleashed the song last year and it soon morphed into a massive viral hit, with its dance themed video becoming the first video to reach one billion hits on YouTube.

Speaking during a talk at Massachusetts' Harvard University, the singer and entertainer suggested that the song's popularity happened by chance. He said:

"'Gangnam Style' was not normal. [It] was not standard - that was an accident and accidents don't happen often."

As previously reported, Psy recently responded by Green Day's Billie Joe Armstrong after the US star likened him to a music equivalent of herpes.

He said: "I kinda like it, it's cool. So he's saying I'm like herpes? I should say something to him. What was his name? Billie Joe Armstrong from Green Day, he's saying I'm like herpes, it keeps coming back. I think it's really cool and I appreciate that. Thank you."