The electoral watchdog is examining claims Pauline Hanson's One Nation may have breached disclosure laws.
Former Queensland One Nation treasurer Ian Nelson told the ABC's Four Corners program on Monday he urged Senator Hanson and chief of staff James Ashby to declare the use of an aircraft, but was told not to worry about it.
Mr Nelson also alleged Mr Ashby had pressured him to conceal the fact that Bill McNee, a Victorian property developer, had donated $70,000 to the party.
A spokesman for the Australian Electoral Commission said the information was "being reviewed in the context of the disclosure provisions of the Commonwealth Electoral Act".
It is understood One Nation was already being looked at as part of a regular program of compliance reviews by the AEC.
Special Minister of State Scott Ryan, who has spoken with AEC commissioner Tom Rogers, is expected to have further talks with the commissioner in coming days.
Labor senator Murray Watt says the AEC needs to check whether electoral laws have been broken, in terms of One Nation's financial disclosure obligations.
Senator Hanson's office declined to comment on Tuesday when contacted by AAP.
Mr Ashby, a registered pilot, told Sky News on Tuesday his company had bought the plane and its use for party purposes had been properly declared.
One Nation senator Malcolm Roberts insisted Senator Hanson may pay for the fuel on her trips.
"The use of the plane is declared as a gift in kind, everything above board," he told Sky News.
"The plane was there before Pauline became a candidate."
Senator Roberts also denied claims Mr Ashby ran a "dictatorship" within the party.
"He is very direct, very honest but he's also personable and engaging. He doesn't get rude and nasty unless someone wants to do that to him," he said.
"He's not a Peta Credlin (former prime minister Tony Abbott's chief of staff) at all, he listens extremely well... he's one of the best people I've ever worked with."
