Queensland’s corruption watchdog has noted a secret recording alleging that James Ashby “proposed to inflate future electoral expenses” for One Nation, but says it will not investigate as the matter is beyond its jurisdiction.

A Queensland police investigation of the affair continues, with Ashby confirming he was interviewed on Thursday.

Ashby told Guardian Australia he spoke to police in relation to allegations by the Queensland Labor senator, Murray Watt, that his remarks could amount to a conspiracy to defraud taxpayers.

Ashby, the chief of staff of One Nation leader Pauline Hanson, said he believed police were “following up” on his complaint about the unauthorised disclosure of a secret recording made by a former party staffer.

Ashby said the party’s lawyers would apply for an injunction next week against the ABC over the broadcast and publication of a series of secret recordings involving him, Hanson and others.

The stream of leaked recordings has jolted One Nation in recent weeks, highlighting the acrimony among former officeholders and party faithful amid the rise of Ashby.

The most recent recording revealed Hanson’s concerns that the media had been told of the alleged donation of a light plane that was not declared to the Australian electoral commission.

The AEC is investigating whether the plane, which Ashby has said he bought for his business use, should have been declared by the party as a gift.

When asked about the recording on Tuesday Hanson declined to respond, saying it was “disgusting” to focus on the issue when a Queensland policeman had been shot dead.

Queensland law permits the secret recording of conversations by people involved in them, but they generally cannot be published unless in the public interest or as part of legal proceedings.

On Friday the state Crime and Corruption Commission released a statement saying it had “completed an assessment of information indicating that Mr James Ashby, the chief of staff of Pauline Hanson’s One Nation Party, proposed to inflate future electoral expenses”.

However, the matter, referred to it by the Queensland attorney general, Yvette D’Ath, was “not within the CCC’s jurisdiction and no investigation will be conducted”.

It said Ashby was “not the holder of an appointment in any Queensland public sector agency and Pauline Hanson’s One Nation is not a public sector agency as defined in the Crime and Corruption Act 2001”.

“There is no information to indicate any person who holds an appointment in a Queensland public sector agency was involved in, or acted on, the proposal to inflate future electoral expenses.”