Vorderman, who has co-hosted the Channel 4 game show since its premiere in 1982, revealed that she was told to take a 90% pay cut or stand down from the programme.
"I was in shock and absolutely distraught at their ultimatum," Carol told the News of the World. "After putting my heart and soul into the show for 26 years I was given just 48 hours to decide - take it or leave.
"To be honest, I loved Countdown so much I was thinking of taking the cut. In fact, in the right circumstances I'd have done it for free - but it was obvious they wanted me out."
Carol announced that she had quit the show on Friday. She was then left furious after bosses leaked information about their dispute to the press, claiming that she had demanded a £500,000 pay rise and the main hosting job.
"I've been all over the place for the past week. All I've ever done, with purity in my heart, has been to work hard for Countdown," she explained. "It's not just like a TV programme to me, that's what's so hard. I hadn't demanded more money and I hadn't insisted on the No1 job. That's all lies. I was pushed into leaving something I love. I was forced out, that's the truth."
Insiders at ITV, which produces the programme for Channel 4, insisted that the ultimatum was necessary as Countdown's budget has been cut.
One source said: "Carol wasn't forced out. Yes, she was asked to take a substantial pay cut but would still have been paid £2,000 a day for sticking up some numbers. Not bad work if you can get it. We make the show for Channel 4 and they cut the budget."
Current frontman Des O'Connor has also confirmed that he is leaving the show.