The Government wants to get out of a prison contract with Serco - but its hands are tied for another 23 years.

Labour is looking for ways to get out of building the billion-dollar prison, which was signed off by the previous government.

Corrections Minister Kelvin Davis said he wants to put an end to privately run prisons and he's looking at ways to exit a deal under which the Government is to build a 1500 bed facility at Waikeria, in Waikato.

Mr Davis said he's looking at all his options to stop it.

But Serco's contract with the Government runs until 2040, and Mr Davis said it would be costly to buy out.

Serco's responsible for running the 960-capacity Auckland South Corrections Facility in Wiri.

It lost its contract to manage Mt Eden Prison in 2015.

Justice Minister Andrew has also said it is his strong preference for the prison not to go ahead.