Union inquiry cleaning up economy: Cormann

Government frontbencher Mathias Cormann has declined to offer advice to royal commissioner Dyson Heydon on whether he should step down.

Mr Heydon, who is presiding over the royal commission into union corruption, is considering his position after the unions accused him of perceived bias.

Their allegations follow his initial agreement to address a Liberal function - an invitation he later declined.

Asked on Ten Network on Sunday whether Mr Heydon should quit, Senator Cormann said: "I'm not going to give him advice.

"He's considering these matters. He's obviously a highly distinguished Australian. He has a great reputation for integrity."

Mr Heydon is expected to hand down his decision on whether he will stay in the role or resign on Tuesday.

Senator Cormann said the commission had been discovering "very concerning stuff" and this was all part of cleaning up sections of the economy so Australia could continue to grow and create more jobs.

"Obviously union corruption hurts our economy. It costs jobs, it imposes massive additional costs across the economy," the finance minister said.

Labor is continuing its attacks on the commission and on Mr Heydon's apparent conflict of interest.

Labor workplace relations spokesman Brendan O'Connor believes the soft approach given to disgraced former union boss Kathy Jackson by the commission highlights its bias.

The Federal Court ordered last week that union whistleblower Jackson pay back $1.4 million to the Health Services Union after it found she misused funds.

"The way in which (the commission) treated Kathy Jackson as a witness with kid gloves compared to other witnesses illustrates the bias I think the council assisting the commissioner has shown towards witnesses," Mr O'Connor told Sky News.