Labour is demanding the release of the contract the government has signed for the construction and running of the new prison at Wiri.
Corrections Minister Anne Tolley launched the $840 million building project in South Auckland on Thursday, saying it would create 1000 construction jobs and 300 long-term positions.
The 960-bed prison will be run by British company Serco and built by Fletcher Construction under a public-private partnership.
Labour's justice spokesman, Charles Chauvel, says Mrs Tolley has a legal obligation to release the contract and suspects she is waiting for parliament to go into recess next Thursday before she does.
"Serco told the London Stock Exchange earlier this month that it expected revenues of 15 million pounds (NZ$29 million) a year from the operation of the prison ... the LSE has more information than the New Zealand public about what the taxpayer will pay under the arrangement," he said.
"This is a contract by which the government will attempt to bind Kiwi taxpayers for 25 years. Parliament was not consulted in advance about its terms and a number of parties, including the principal opposition party, oppose the principle of private sector management of prisons."
Mr Chauvel is challenging Mrs Tolley to release the contract before parliament goes into a two-week recess.