The veteran broadcaster said his former employer “unilaterally” cancelled his exit deal and he “couldn’t be happier” to have severed ties following his departure from GB News earlier this month.
A GB News spokeswoman told PA the channel had no comment on the remarks.
The presenter, who was also chairman of GB News, tweeted on Wednesday evening: “After weeks of talks with @GBNEWS, resulting in exit settlement, the channel then broke it by briefing Mail on Sunday with load of smears/lies then unilaterally cancelling exit deal.
“Leaving me free to do, say whatever I want + never again be on GBNews. Couldn’t be happier.”
A report in the Mail on Sunday cited a leaked memo claiming Andrew was about to be sacked before he walked.
The former BBC presenter had been chairman of the fledgling channel and its most high-profile star when it endured a troubled launch in June.
He took a break two weeks after the launch. Reports of a difference of opinion between him and other senior executives soon followed.
Initially, it was said he would still appear on the channel as a commentator.
However, he appeared on Question Time last week and said he had been in a “minority of one” over the future direction of GB News, which has been accused of trying to import Fox News-style journalism to the UK.
“More and more differences emerged between myself and the other senior managers and the board of GB News,” he said.
“Rather than these differences narrowing, they got wider and wider and I felt it was best that if that’s the route they wanted to take then that’s up to them, it’s their money.
“The route is what I think you can see on GB News at the moment, people should make up their own minds what they want to watch.”
After the Question Time appearance, GB News issued a rebuttal.
It said: “During last night’s BBC Question Time, a number of demonstrably untrue remarks were made about GB News. We stand for fair debate, tolerance, free speech and factual journalism. There are always more than two sides to any story and we believe in listening to all of them.”
A number of big names joined the channel for its launch including ITV News journalist Alastair Stewart, BBC journalist Simon McCoy and former Labour MP Gloria De Piero.
Guto Harri quit the channel following a row over him taking the knee during a debate on the racism directed towards England football players, while other staff members have reportedly left.