Frankie Muniz takes savage swipe at Hilary Duff's mum as he reveals actors haven't spoken for 22 years

Over two decades since they starred together in Agent Cody Banks, actor Frankie Muniz has this week revealed where it all went wrong for he and childhood friend Hilary Duff.

For those in need of a reminder, the former child stars first met as teenagers, with their on-screen careers kicking off around the same time.

Whilst Muniz was cast in Malcom in the Middle - a role for which he was nominated for both an Emmy and two Golden Globes - Duff sky-rocketed to international stardom after landing the titular role in Disney Channel's Lizzie McGuire.

In the years that followed, Muniz went on to appear in the coming-of-age sitcom, making a cameo as himself, forging a close friendship with Duff in the meantime.

And by 2003, they were announced as the two lead stars in the spy-comedy Agent Cody Banks, which also starred Angie Harmon, Keith David and Ian McShane.

Frankie Muniz and Hilary Duff starred together in the 2003 spy-comedy (KMazur/WireImage)

In the years that followed, given the pair's electric dynamic, TV fans expected Muniz and Duff to cross paths for a sequel or two, but were left sadly disappointed when only Muniz returned for Agent Cody Banks 2: Destination London.

Onlookers assumed that a fall-out had occurred behind the scenes, a theory confirmed by a 39-year-old Muniz this week.

Speaking on an episode of the Joe Vulpis podcast, the actor - who has since transitioned to professional race-car driving - looked back on his entertainment career, during which he reflected on his relationship with Duff.

"We became really, really good friends," he began. "We had a really great relationship for a long time."

In a shock confession, however, Muniz alleged that his former co-star's mother had been to blame for the duo's friendship fizzling out, claiming Susan Duff had interfered in the casting process of Agent Cody Banks to secure her daughter the lead female role.

Muniz has been looking back on his acting career (Gabe Ginsberg/Getty Images)

"I was on the set of Lizzie McGuire, and I was in Hilary’s dressing room and her mom was there," he continued.

"Her mom was like, 'Do you know what you’re doing this summer? What are you doing this summer?'.

"And I go, 'Oh, I’m filming this movie where I’m playing like a junior James Bond'."

Muniz went on to claim that, after he told Susan all about the upcoming flick, she'd asked whether a female lead had yet been cast, to which he replied that Smallville actress Kristin Kreuk was a shoe-in.

He added that the next time he and Susan spoke, she revealed that Duff had since been cast in the role.

Muniz claims Duff's mother interfered in the casting process (Amy Graves/WireImage)

"Her mom’s like, 'Guess what? We’re going to be spending the summer together - she’s doing Cody Banks with you, they signed her last night'," Muniz recalled, claiming he immediately thought to himself: "'The movie you knew nothing about yesterday?'."

The father-of-one continued: "Needless to say, I wasn’t thrilled about it. And not because I didn’t want it to be Hilary.

"I don’t know how much I want to say. I’m trying to think about it because I’ve already said way too much.

"I was very sad when Hilary’s mom would come on set - and if I told you I’ve never talked to Hilary since the last day of filming. I’ve not said one word to her since then.

Muniz claims he regrets his fallout with the Duffs (Cindy Ord/Getty Images for SiriusXM)

"So that’s the truth of that. No one knows about my Hilary Duff story."

Muniz did go on to insist that he harbours guilt over how his relationship with the actress was left, adding: "I regret not just continuing to be friends with her because we had a great friendship for such a long time, and I let her mom - it p*ssed me off.

"I would love to catch up with her [in the future]. I would love to even talk about that because I’m sure she doesn’t know any of that happened."

Tyla has contacted Duff's reps for comment.