Corrections Minister Judith Collins says double bunking of prisoners is now essential to manage the prison capacity crisis.
A post-election briefing by the Corrections Department warned that prison capacity was a looming crisis. It forecast that beds would run out by the middle of next year.
But Ms Collins says it's now estimated that prisons will reach capacity by about February.
She has asked the Corrections Department to speed up adding container cells to prisons to house inmates - but that won't be enough.
Ms Collins says negotiations are also under way with the Corrections Association to expand the number of cells that hold two prisoners.
