British comedian Russell Brand has opened up about his ex-wife Katy Perry's new romance with serial dater John Mayer, insisting he is no longer in a position to "protect" her.

The funnyman's 2010 marriage to the I Kissed A Girl hitmaker broke down after just 14 months, and their divorce was finalised last July (12).

Perry has since gone public with her new bad boy beau Mayer - and former wildman Brand admits it's been hard to watch his ex get serious with a known womaniser, thanks to his relationships with Jessica Simpson, Jennifer Aniston and Taylor Swift, among others.

The actor was quizzed about his thoughts on the Perry/Mayer romance during a candid radio chat with his pal Howard Stern on Monday (04Feb13), when the Dj asked, "What do you make of your ex-wife dating John Mayer? Doesn't she know that he's a worse womaniser than you?"

Brand jokingly replied, "Worse or better, depending on how you view it", before adding, "You have to let go of the instinct to protect someone once you divorce them."

And the Forgetting Sarah Marshall star had nothing but kind words to say about Perry. When questioned about her body, he responded, "That woman was perfect from top to bottom."

Meanwhile, Brand insists he is single, despite reports linking him to actress Demi Moore: "I'm not dating anybody. Actually, I'd like a romance. (I'm) just going through life, meditating, doing yoga, concentrating on this Tv show and trying to find a nice wife."