The Green Party has dipped into its taxpayer funding to illustrate SkyCity's proposed expansion of its gambling floor, but the party says the cost of its stunt in Aotea Square is negligible compared with the money the Government spent negotiating a deal with the casino.

The Greens have created a cardboard replica of the additional 510 gambling machines and 40 gambling tables that Sky City would be able to install in exchange for building a convention centre in Auckland.

Greens co-leader Metiria Turei said the display was designed to remind politicians and Aucklanders of the scale of the concessions granted to the company.

"Until you see it laid out, it's hard to understand the fact that this is effectively the third largest casino in the country."


She said the pokies-for-convention centre deal went against the principles of the Gambling Act, which blocked casino growth, and made a mockery of Auckland's sinking lid policy on pokie machines.

The cardboard casino would be taken to Parliament when the convention centre legislation returned to the House.

"We still only need one vote to defeat the bill," said Ms Turei. The legislation would be decided by a conscience vote instead of along party lines and the Opposition has been encouraging the public to put pressure on National's backbench MPs to cross the floor.

In exchange for paying for a $400 million convention centre, SkyCity would get further regulatory concessions including a 30-year extension to its gambling licence, cashless gambling, and protection against future law changes.

The Greens' cardboard display cost around $3300 - $2150 for the materials and $1150 to book Aotea Square. A spokesman said it was funded from the party leaders' office budget and had been approved as legitimate spending by Parliamentary Service.

Submissions on the New Zealand Convention Centre Bill will be heard at Parliament on Thursday.