Christopher Eccleston's relationship with his "Doctor Who" superiors "broke down" on the set of the programme.
The 54-year-old actor had a short-lived spell as the Time Lord in 2005 - when he starred alongside singer-turned-actress Billie Piper, and Russell T Davies was showrunner - but he lost the sci-fi role in abrupt fashion, claiming his bosses "lost trust" in him.
He explained: "My relationship with my three immediate superiors - the showrunner, the producer and co-producer - broke down irreparably during the first block of filming and it never recovered.
"They lost trust in me, and I lost faith and trust and belief in them."
Christopher doesn't think he was a natural fit for the light-hearted role, and he's suggested his discomfort could have contributed to his on-set unhappiness.
He told the Radio Times: "Some of my anger about the situation came from my own insecurity.
"They employed somebody [as the Doctor] who was not a natural light comedian."
Christopher explained that his own insecurities were compounded by Billie's anxieties.
He reflected: "Billie [Piper], who we know was and is brilliant, was very, very nervous and very, very inexperienced.
"So, you had that, and then you had me. Very, very experienced, possibly the most experienced on it, but out of my comfort zone."
Christopher claimed that when he left the BBC show, he reached an agreement with Russell that prohibited him from discussing the reasons for his exit.
But Christopher has performed a U-turn on that promise over recent months.
The star explained: "When I left, I gave my word to Russell T Davies that I wouldn't do anything to damage the show.
"But they did things to damage me. I didn't criticise anybody."