In a heated exchange, federal government frontbencher Arthur Sinodinos has accused Shadow Treasurer Chris Bowen of conflating two issues as he stands by his decision not to front a Senate committee.

Labor wanted Senator Sinodinos to appear before a committee investigating political donations, which it set up on the last sitting day of Parliament.

“The situation is that Arthur was chairman of a company and treasurer of a political organisation, the company he was chairman of was making donations to the political organisation he was treasurer of and he says ‘I know nothing’,” Mr Bowen told Radio National during a segment with Senator Sinodinos.

• Biggest challenge for new ABC boss
• Climate policies compared
• Labor’s plan ‘carbon tax on steroids’: govt

The Senator hit back, saying “Chris Bowen just mixed two different situations up, he doesn’t even know what the inquiry is about… to talk about a… got nothing to do with a company.”

“Well the situation is Arthur that you’ve been…” Mr Bowen interjected.

“Have you read, have you actually read the, mate, have you actually read any of the evidence?” Senator Sinodinos asked.

The first issue is the New South Wales Liberal Party being found to have used a body called the Free Enterprise Foundation to offer anonymity to political donors, including property developers, who are banned from making political donations to NSW campaigns.

The state’s corruption watchdog investigated the issue but Senator Sinodinos, who was the NSW party’s treasurer at the time, was not a focus of the inquiry.

The second issue is Senator Sinodinos’s role as a director of Australian Water Holdings, a company which remains the subject of a NSW Independent Commission Against Corruption (ICAC) inquiry.

The Senate inquiry Labor wants the Senator to front was set up after the New South Wales Electoral Commission decided to withhold $4.4 million in public funding because of the political donations disclosure issue.

In a letter obtained by the ABC, Senator Sinodinos criticises the Senate committee’s handling of the inquiry.

“Given that the calling of a federal election is imminent, the public might be forgiven for concluding that this inquiry is nothing but a political stunt, not a bona fide attempt to inquire into an important question of public policy,” he wrote to the chair of the committee.

“I note that Senator Nick Xenophon has described the proceedings as having the appearance of a ‘witch hunt’.”

He suggested the committee had overstepped its powers in calling him to appear, and that he was not available for either of the two dates the committee will be sitting.

Opposition Senate leader Penny Wong has defended the inquiry as necessary for “making sure our electoral system is robust”.

– ABC