"Unforeseen delays" have hit the new $300 million rebuild of the outdated Auckland Prison at Paremoremo on the North Shore, the Department of Corrections says.
Last year, Corrections said the buildings - which include New Zealand's only maximum security unit - were due to be finished in December and prisoners were due to move by March.
But three months later, Corrections admitted this month that no prisoners had been moved because of issues with the job.
"The construction of the new Auckland Prison is complete. Projects as big and as complex as this can, at times, develop unforeseen delays in the construction process," a spokesperson said.
"These were addressed by the contractors at no cost to Corrections."
Fletcher Construction - hit by cost over-runs and problems on other sites - is the lead contractor at the project, which is Corrections' biggest development.
Last May when the Herald visited, more than 700 workers were on the site and a spokesperson said at the time that by March this year, 690 prisoners would be housed in the facility.
Fletcher worked with Firth Concrete to invent new "maxi-security" construction blocks especially for the prison. Stuart West of Fletcher said last year those blocks weigh 17kg each, compared with a standard 12kg block.
A Fletcher spokesperson said the company had nothing further to add to what Corrections had said.
The Corrections spokesperson said this month that prisoners would begin moving in July.
"Corrections is now working to ensure the operational effectiveness of the site and is beginning to transition staff into the facility. The transfer of prisoners is expected to begin next month," the spokesperson said.
"The $300 million development has been designed with safety and security as the highest priority. The new facilities are designed to improve staff and prisoner safety, prisoner engagement in rehabilitation and reintegration activities and enhance our ability to meet the needs of prisoners with severe mental illness," he said last May.
The new prison will have heart-beat detectors, security doors that unlock with a fingerprint scanner and a five-layered fence.
Work has taken place on the 54.7ha site for the last four years.
Last year, Andy Langley, Auckland Prison director, said the new buildings replaced much of the nearby 1968 jail and improved conditions for prisoners, staff and visitors.
"It becomes higher security than it was because there's a single point of entry, whereas the existing prison has multiple entry points, the fabric and design is at a very high level, and the perimeter fence has five detection layers," Langley said last May.
"There's a lot of separation internally as well as within each cell and unit," Langley said.
New standard accommodation maximum security cells have showers and are 9.09sq m, compared with old 5.81sq m cells.
All cells are on the ground floor, with staff areas above, compared with the old three-level buildings which created stair-movement safety problems.
Corrections had last year made no decision about the old jail.
"We don't know what we will do with the east wing. Our plan is to close this facility. The condition of it is such that it's so old, we have leaks, the concrete is very brittle and falling away. It needs replacing," Langley said at the time.
The western part of the old facility would remain accessible by a tunnel. The layout of the old prison is traditional, created according to principles of the Victorian era, he said.