He made a shock exit from The Office following its seventh season.

And Steve Carell's unexpected departure from the show appears to have finally been explained, as new book The Office: The Untold Story of the Greatest Sitcom of the 2000s seemed to reveal the reason on Wednesday.

The show's boom operator and sound mixer Brian Wittle, who was interviewed in the book, claimed the actor, 57, left the role because showrunners didn't react when he 'haphazardly mentioned' the seventh season could have been his last.

Hard decision: Steve Carell made his shock exit from The Office because showrunners 'didn't call' after he accidentally suggested he depart in an interview, it was revealed on Wednesday

Brian explained: 'I sat with [Carell] one time and he told me the story. He was doing a radio interview and he haphazardly mentioned, almost unconsciously, that it might be his last season.

'He didn't plan on saying it out loud and he hadn't decided anything. Then what he said was the people connected to the show had no reaction to it.

'They didn't call and say, "What? You wanna leave?" He said he didn't get any kind of response from them…

'When the news broke that he was considering it, the people that are in charge of keeping him there didn't make a big effort to do so until afterward.'

Iconic: Steve portrayed Michael Scott for seven seasons (pictured), but left after there was no reaction when he 'he haphazardly mentioned, almost unconsciously, that it might be his last'

Reiterating Wittle's story, hairstylist Kim Ferry said of the actor's departure: 'The deadline came for when they were supposed to give him an offer and it passed and they didn't make him an offer.'

Casting director Allison Jones also told the same story, as she explained: 'As I recall, he was going to do another season and then NBC, for whatever reason, wouldn't make a deal with him…

'Somebody didn't pay him enough. It was absolutely asinine. I don't know what else to say about that. Just asinine.'

Steve portrayed bumbling boss Michael Scott on The Office, who was himself based on Ricky Gervais' character David Brent in the BBC original.

The American mockumentary followed the everyday lives of employees of the Dunder Mifflin Paper Company, of whom Scott managed until the seventh season.

Steve's character departed the show after proposing to HR representative Holly Flax, before moving to Colorado with her so they could take care of her aging parents.

The Office continued for a further two seasons without Steve, before ending in 2013 with its ninth season.