Mr Rattenbury told the ACT Legislative Assembly on Tuesday evening he would not be "intimidated" or "silenced" by the "bullying tactics" of the Canberra Greyhound Racing Club, who have launched defamation action against him.

"The defamation threat they have made against me is a classic SLAPP suit – strategic litigation against public participation – historically a tactic used by dodgy developers to silence community activists and provide a chilling effect on media reporting of issues," Mr Rattenbury said.

Hadley used his talkback radio show on Wednesday morning to accuse Mr Rattenbury of being "cowardly" going into parliament to make "unsubstantiated" allegations.

"Who's the bully here Rattenbury? The Canberra Greyhound Racing Club or you, hiding behind parliamentary privilege you grubby little man? He makes a whole range of accusations which can't be substantiated," Hadley said.

"He's a Green. And he's a grubby little Green. By the way Shane if I were to call you a grub that would be defamatory. Calling you grubby is not. So I'd never call you a grub Shane Rattenbury, I'd call you grubby. And looking at a photo of you in the Canberra Times, you do look like an unmade bed, rather dishevelled and grubby. Poor Canberra having you represent them."

Mr Rattenbury's office was contacted for comment.

Hadley's spray comes as the ACT Gambling and Racing Commission confirmed an investigation into 30 suspect swabs Mr Rattenbury referred to in his speech had not yet finished.

Club spokesman Kel Watt had told Fairfax Media the investigation had vindicated the club last month and accused Mr Rattenbury of using his parliamentary privilege to "mislead".

"We would have liked him to complete the story, the Gambling and Racing Commission found there was no cause for concern and no substance to the allegations early last month," Mr Watt said.

Mr Watt said he had been advised by the steward and club the probe had closed and apologised for the error.