The Green Party wants to introduce a scheme that would require members of the Government to regularly disclose who they meet.
The party issued a proposal on Saturday to introduce a ministerial disclosure regime based on a system used in the United Kingdom since 2010.
It would require all Government ministers to release records every three months of their meetings with external organisations, overseas travel, and gifts and hospitality they've given or received.
Party co-leader Metiria Turei said some of that information is already available through the register of pecuniary interests.
But Ms Turei says that does not tell the whole story and it happens only once a year.
She says the change is needed because people are buying access to ministers.
She said a disclosure scheme would increase the Government's transparency and accountability.
In an interview, Ms Turei said the party would like extend this requirement to all MPs, but the use of ministerial influence is the big issue at present.
Justice Minister Judith Collins has been under pressure to reveal the details of a private dinner she attended in China that was organised by the milk export company Oravida.