Shrek, the hit Dreamworks animated film, is celebrating its 20th birthday this month.

New Zealander Andrew Adamson, who hails from Auckland, was one of the film's two directors alongside Vicky Jenson, and told Mike Hosking the success it generated took him by surprise.

"I had no idea what was going to happen. There was a point after a test screening when Jeffrey Katzenberg... had made The Lion King, sort of said to me 'be prepared for this Andrew, this probably will only happen once in your lifetime'... and I didn't really know what he meant by that."

Adamson says at the time Shrek was "very" cutting-edge from a technological perspective, and in this day and age, is still a fan favourite.

"I still have parents of young kids come up to me and thank me for it.

"It's the first movie I ever directed, and I'm very pleased obviously that it came out well and I'm really pleased  that it's not a cynical move, it's a very heartfelt film."