Treasury secretary Steven Kennedy is disappointed he signed off on the $33 million Western Sydney Airport land deal when he was running the infrastructure department.

The parcel of land was only worth $3 million.

Dr Kennedy headed the Department of Infrastructure between September 2017 and September 2019, during which time the land deal was done.

He said while the valuation occurred prior to taking on the role, it was not signed off until he was leaving the department to take the top job at Treasury.

“I thought it was unreasonable to leave a new secretary to have to sign off on the financial statements of the year that I just oversaw,” Dr Kennedy told a Senate estimates hearing in Canberra on Monday.

“I chose to sign them off. I didn’t appreciate the significance of this matter.”

Dr Kennedy said he was subsequently “surprised and concerned” by the findings of a scathing auditor-general’s report, which uncovered unethical behaviour and information being withheld from decision makers.

He was given an opportunity to comment on the report but declined.

Instead, he is waiting to see what an independent investigation finds in relation to what systems he should have had in place as secretary.

“I’m not pleased, no one would be pleased as a public servant, and I am very disappointed, it is now reflecting poorly on all of us,” Dr Kennedy said.

“We have got to get to the bottom of this and find out why the system didn’t bring this to a head.”