Infrastructure Minister Bill English says the Government will do deals with private companies only if it is in the best interests of taxpayers.
Mr English told an infrastructure conference in Wellington on Wednesday that the Government does not have to build and own everything, including schools and prisons.
He later told reporters that the Government was still considering having prisons not just built, but also run by private companies.
Mr English said the proposal will go ahead only if private prisons are cheaper to run and work better than state-run prisons.