The centre branded Australia's lobbying regulations as narrowly scoped, full of loopholes and having limited integrity and enforcement, in an analysis of the sector.
A spokesperson for Attorney-General Michelle Rowland said the federal government was "committed to upholding a high standard of integrity, transparency and accountability".
"Including ensuring that lobbying of Australian government representatives is carried out ethically and transparently," the spokesperson told AAP in a statement.
A code of conduct places obligations on third-party lobbyists and government representatives for transparency purposes, the spokesperson said, noting "lobbying is a legitimate and important part of the democratic process".
"The government regularly reviews the policy settings for the code, taking into account a wide range of views," they said.
But the centre criticised the code of conduct for not being legislated or having independent oversight outside a government department.
It also criticised the "revolving door" of politicians and their staff leaving politics and taking advantage of their position to court former colleagues with little to no regulation.
The centre called for a minimum three-year cooling-off period that covers all ministers, parliamentarians, advisors and senior officials.
Ministers are currently banned for 18 months and their staff for one year after leaving their roles.
Some 40 per cent of lobbyists on the federal register disclosed a former political association at the end of the 2024/25 financial year, the report noted.
"Many lobbyists are former government officials or politicians, raising concerns that insiders can trade on their public past for private gain," it said.
The centre also recommended scrapping "success fees" for lobbyists, broadening the definition to capture more people, the timely disclosure of meetings, imposing serious penalties and installing an independent regulator.
Crossbenchers senator David Pocock and Monique Ryan are pushing legislation to improve transparency around lobbying.
Greens senator Steph Hodgins-May also promised to pursue legislated reforms with the minor party holding the balance of power in the Senate.
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