NDHB chairwoman Sally Macauley said she could reassure the people of the Mid North that the Bay of Islands Hospital rebuild was underway and would continue as planned.
The health board would now also take over the wellness centre project, which would bring together the three GP practices in Kawakawa and Moerewa, along with community health, outpatient, pharmacy and dental services.
It was too early to discuss how the extra cost would be met. More details would be available soon, she said.
Ngati Hine Health Trust chief executive Geoff Milner and chairwoman Gwen Te Pania-Palmer did not return the Advocate's calls on Friday.
The hospital rebuild includes a new two-storey building with an accident and medical department, radiology and after-hours GP service on the ground floor and a 20-bed medical ward upstairs. The remaining part of the old hospital will be refurbished.
As well as housing most of the area's primary health services, the adjoining wellness centre will form the entrance to Bay of Islands Hospital.
When the project was launched in May, Mrs Te Pania-Palmer said the combined heath board-health trust project would offer the best care possible for all people of the Mid North.
She said the wellness centre would be by far the trust's biggest investment to date, easily eclipsing Te Mirumiru early childcare centre, built in 2012.
A decision to build the combined facility on the Bay of Islands Hospital site in Kawakawa came after years of debate over whether to rebuild the old hospital or start again on a new site elsewhere in the Mid North, such as Kerikeri.