The Australian Electoral Commission has launched a formal investigation into the funding of a $100,000 private aircraft used by Pauline Hanson's One Nation.

Electoral Commissioner Tom Rogers confirmed the AEC had already been conducting an inquiry into the party, and revealed a further investigation was authorised in early May.

The Jabiru light aircraft, used extensively by the party for campaigning purposes, has been the subject of increasing scrutiny. Senator Hanson and her chief of staff James Ashby have offered differing explanations for its omission from the usual disclosures about political donations.

"The commission started off a process of inquiring of a number of people involved in that process ... seeking information voluntarily so we could piece together some facts," Mr Rogers told a Senate hearing late on Thursday night.

The AEC is employing "rarely used" powers to compel people to provide information once they have been issued with notices.

"With the issue of those notices, this matter ceased to be an inquiry?? and became a formal investigation," Mr Rogers said.

The aircraft in question is emblazoned with One Nation branding and has been used by Senator Hanson and Mr Ashby since 2015.

It has been reported that it was donated by party backer Bill McNee but Senator Hanson has insisted the wealthy developer purchased it and allowed the party to use it.

Mr McNee has denied purchasing the plane and Mr Ashby has previously said he himself bought the plane for his business and recreational purposes.

In an episode of Four Corners in April, former One Nation treasurer Ian Nelson claimed he urged Senator Hanson and her high-profile chief of staff, James Ashby, to disclose the donation, but was overruled.

Confirmation of an investigation has emerged as the party fights battles on multiple fronts.

Mr Ashby has been forced to defend himself after the leaking of an explosive recording, in which he proposed a scheme to make money off candidates and government campaign funding, and a key staffer has been charged with several counts of assault and been taken into custody.

In the recording of a party meeting, Mr Ashby is heard outlining "an opportunity for us to make some money" in the Queensland election, by inflating what the party charges candidates for campaign materials and claims back from the state's electoral commission.

Senator Hanson and Mr Ashby later denied any wrongdoing had taken place.

Mr Rogers said the AEC had conducted a preliminary review of the recordings, but would not be investigating the matter further.

"As far as I'm aware, there are no offences against the Commonwealth Electoral Act that have been disclosed by those actions," he said.

"That doesn't mean there won't be other Commonwealth offences under other laws."

Labor, in referring the recordings to the Australian Federal Police, Queensland police and Queensland electoral commission, has accused One Nation of seemingly engaging in a "conspiracy to defraud taxpayers".

with AAP