The capacity of the proposed International Convention Centre falls under the limits the founding study on the project said was needed to make it viable for a return to the economy.
"To improve economic growth New Zealand needs a centre that can accommodate an average of 3500 delegates in a plenary session," the report for Auckland Council and the Ministry for Tourism found in 2009.
Resource application documents filed with Auckland Council show the "Plenary Hall" has a maximum capacity of 3000 people - well short of an "average" 3500 delegates - and could drop further with talks of 10 per cent cuts to the centre.
Economic Development Minister Steven Joyce told the Herald this week that the ability to host fewer delegates in the main exhibition hall was not a major concern.
"Within the margins you could cope with a few things if there was a benefit in terms of the savings, and that meant they didn't have to cut back on the look of the place."
The 2009 feasibility study was the foundation document for the convention centre. It was funded with a $250,000 grant personally approved by Prime Minister John Key, adding to $20,000 contributed by Auckland Council.
Mr Key said at the time: "If the recommendations from the feasibility study are positive, I expect we will prepare a detailed business case and an establishment plan to develop a large international conference centre in Auckland."
The taxpayer-funded feasibility study in 2009 found an operational Auckland-based convention centre would bring in $85.4 million in tourism-related spending each year.
A SkyCity spokesman said the exhibition hall would be able to host 3500 people if more space was needed than the Plenary Hall allowed.
A spokeswoman for Mr Joyce said there were no plans to review the deal with SkyCity.
"The Crown will retain the right to reject any amended designs proposed by SkyCity if it does not think an international-standard convention centre will be built."
She said the data used for the economic analysis had not changed "significantly" since the report was published.
Green Party co-leader Metiria Turei said an independent study was needed into the SkyCity deal.
"The revised design puts the whole project at real financial risk. The Government doesn't have any control over this."
Bums on seats
John Key's 2009 feasibility study:
"To improve economic growth New Zealand needs a centre that can accommodate an average of 3500 delegates in a plenary session."
SkyCity's 2014 resource consent application:
"The NZICC's most significant components include a 3000-seat Plenary Theatre for Plenary sessions presentations to delegates .