One Nation senator Malcolm Robert says his party leader has nothing to worry about from investigations into its affairs because "everything is above board".
The Australian Electoral Commission is investigating whether One Nation has breached disclosure laws in relation to a Jabiru light aircraft used by Pauline Hanson.
The Australian Federal Police, Electoral Commission of Queensland, Queensland police and Queensland Crime and Corruption Commission are also making enquiries into aspects of the party's funding.
Senator Hanson indicates in a recorded conversation leaked to the media on Tuesday a Victorian property developer Bill McNee donated money to the party to cover a year's rent on its Brisbane office and the plane.
Her chief of staff James Ashby has said the plane, which is registered and insured in his name, was bought by his Queensland company.
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Senator Roberts said Mr Ashby and Senator Hanson were "completely trustworthy".
"I just accept what she says because I've been dealing with her now for 12 months and she is just fabulous, she is straight up," Senator Roberts told Sky News.
"The slightest thing deviating from the truth she quickly corrects it - she is very strong on integrity and the same with James."
Asked why Senator Hanson indicated in the phone call she wanted to keep Mr McNee's identity a secret, Senator Roberts said: "I've never met Bill, but he's a very private person."
