The actor and trade union activist said a documentary fronted by the broadcaster was government propaganda that swayed a jury that convicted him for offences linked to the 1972 builders' strike.
Tomlinson told the Chester Chronicle he has leaked classified documents showing late prime minister Sir Edward Heath and Conservative MP Woodrow Wyatt were involved in a conspiracy to jail a group of striking workers, known as the Shrewsbury 24.
However a campaigner who has spent a decade investigating the prosecutions said they had found no evidence to suggest Whiteley was connected to the security services "in any way".
His partner, Kathryn Apanowicz, said the claim was "laughable" and suggested Tomlison had concocted the story to get publicity.
The Royle Family and Brookside star said two jurors in the 1973 trial changed their verdicts after the documentary, Red Under The Bed, was broadcast by Yorkshire Television as the jury deliberated.
He told the Chronicle: "We found out this week that the film was designed, written, made and paid for by the security services.
"Woodrow Wyatt was a member of the security services and, unbelievably, so was Richard Whiteley, who hosted the show.
"Richard Whiteley from Countdown was a member of the intelligence services."
Whiteley died in 2005 aged 61 after undergoing heart surgery.
Ms Apanowicz, 56, said he could not have been a spy as he "couldn't keep a secret to save his life".
"It is absolute bloody nonsense, there is no truth in it whatsoever," she told the Daily Mail.
Gyles Brandreth, a friend of the late presenter who regularly appeared in Countdown's dictionary corner, was sceptical about the claim, while former Conservative MP Jonathan Aitken told the newspaper: "I knew him pretty well and my guess is this is pretty good baloney."
However Carol Vorderman remembered Whiteley as a "mystery" man. "I would be fascinated to see Ricky's evidence," she told the Daily Mail.
Eileen Turnbull, a researcher for the Shrewsbury 24 Campaign, told the newspaper: "I believe firmly that there is factual evidence to show that there was government interference in the charges that were brought against the Shrewsbury pickets and in the trial itself.
"But we have found no evidence to support the view that Richard Whiteley was in any way connected to the security services, he was just the presenter."