Finance Minister Mathias Cormann has defended his department's process in the Western Sydney Airport land sale debacle, but says the appropriate inquiries must get to the bottom of it.
The $30 million sale in 2018 for land worth just $3 million was "highly unsatisfactory", Senator Cormann told a Senate estimates hearing on Wednesday.
He said the secretary of the Department of Infrastructure has acknowledged that and a AFP investigation is under way.
"We must get to the bottom of this," Senator Cormann said.
But Labor's finance spokeswoman Katy Gallagher questioned how something like this got through without the appropriate checks and balances.
"I get that the infrastructure department is up to its eyeballs in this, but I'm trying to find out what Finance knew," Senator Gallagher said.
"You can't say it is everyone else's fault."
Senator Cormann said if there was any issue with the involvement of his department, he would be the "first to jump up".
"I take a lot of comfort from the fact that the ANAO (Australian National Audit Office), who actually brought this to the fore ... not a single finding, not a single recommendation directed at Finance," he said.
Australian Associated Press