A Parliamentary committee is being urged to publicly release a report into the Auditor-General, who resigned this week.

Martin Matthews stepped down on Thursday - an hour before a report into his handling of the Joanne Harrison fraud case at the Ministry of Transport was tabled in Parliament.

Anti-corruption group Transparency International New Zealand says in any society that wants to be corruption free it's very important to release public documents.

Director of Ethics Charles Hett says there are also other reasons it should be released.

"There's no doubt that not releasing the report runs the risk and is probably causing unnecessary speculation as to the contents."

Mr Hett said in any society that wants to be corruption free it's very important to release public documents.

"If there are some lessons to be learnt then the only way we're all going to learn them is by reading the report and finding a better way of doing things."