A former judge of Victoria’s highest court has attacked the Coalition’s proposal for an anti-corruption body, describing it as a sham designed to shield politicians and public servants from scrutiny.

Stephen Charles, a retired Victorian court of appeal judge, said there was simply “no justification” for the Coalition’s proposal to limit the commission’s powers when investigating the public sector. He said the proposal to not allow public hearings for public-sector cases – as opposed to investigations of law enforcement – made no sense. Nor did the proposed body’s narrow remit, the high burdens of proof needed to initiate an investigation, its inability to take public tip-offs and its lack of resources.

“We see this body, the [Commonwealth Integrity Commission], insofar as public servants and parliamentarians are concerned, as a sham,” he told Guardian Australia. “It’s not really an anti-corruption commission at all.

“It’s a body set up to shield parliamentarians and public servants.

“It’s a very glitzy model filled with all the bells and whistles but it masks the fact that it’s not an anti corruption [body] at all in so far as public servants are concerned. And the public servants are where the really large money is going.”

The Coalition’s model for an integrity commission was released late last year. It drew early criticism for not allowing public hearings or public tip-offs. The body is also only able to begin an investigation if it is satisfied to a high threshold of suspicion that a crime has been committed.

Transparency International Australia, one of the key anti-corruption agencies lobbying for a federal integrity commission, also criticised the narrow focus of the reform. The group said major improvements were needed to systems governing lobbying, donations and a revolving door between politics and big business.

“The administration and enforcement of the lobbying code of conduct, register of lobbyists and policies, rules and standards for the post-separation employment of commonwealth public officials be given a statutory basis,” Transparency International said in a submission to a parliamentary inquiry.

“There is a need to revise and update commonwealth legislation and enforcement for transparency, integrity and accountability in political campaign finance and campaign regulation to meet national and international best practice.”

Transparency International said a proposal from the crossbench MP Cathy McGowan for a national integrity commission was far preferable to that proposed by the government.

“The NIC bills provide a more comprehensive and coordinated approach to addressing issues of parliamentary integrity and preventing, detecting, investigating and disclosing corruption than the Commonwealth Integrity Commission (CIC) model as currently proposed by the attorney general, the Hon. Christian Porter MP.”