Frankie Muniz was the title star of hit sitcom Malcolm in the Middle, but now he’s explained why there are two entire episodes where he doesn’t appear, after he walked off set.

News.com.au website reports that the American former actor was sharing confidences with his campmates in I’m A Celebrity Australia when he revealed:

“There were two episodes I’m not in. I walked off the set.” And he explained his actions were because tension on set had reached boiling point, because of the behaviour of other “certain people.”

“Everyone was so afraid to stand up when certain people were controlling or rude or disrespectful. Like they walked on pins and needles,” he remembered.

“I was so mortified by seeing people afraid to stand up for themselves, I was like: ‘Say something.’

“I didn’t care if they told me I was never going back, because it was worth it to me. It helped that the show was based around me.”

Muniz, who starred as middle brother Malcolm in the hit show from 2000 to 2006, retired afterwards to become a racing driver, and revealed he had become much happier since leaving behind the entertainment industry and LA.

Before entering the South African jungle for I’m a Celebrity, he told news.com.au:

“I never felt like I fully fit in the Hollywood world, even though I was in the world. I was nominated for Emmys and Golden Globes, and I was going to all this stuff, and I was there, and I was like, how am I here?

“I hated LA, so I kind of stayed in my own little world, my own little bubble. And moving to Arizona, I did it on a whim, and I realised immediately that I started looking up.

“I started enjoying looking at trees and birds in the sky. Going to the grocery store was a fun thing. You don’t get that in LA. It’s a miserable experience.”

As well as his lead role on TV, Muniz starred in hit movies including Agent Cody Banks, Big Fat Liar, and Racing Stripes.