Auckland health officials say tough standards will be required of both firms now providing community medical testing in the region and the results will be reported to the public every month.
Radio New Zealand's health correspondent says it is the latest twist in a long-running saga over which of two competing Australian-owned firms should hold the $560 million, eight-year contract for the service.
On Tuesday Diagnostic Medlab Limited won back 10% of the regional contract for the work amid ongoing concerns that new provider Labtests is not improving its service fast enough.
Auckland district health boards say they are giving DML a four-year contract for tests involving private hospitals, private specialists, private home visits, fertility treatment and resthomes.
At a cost of $4.4 million a year, DHBs are also allowing Labtests to keep its eight-year contract for all other community testing.
Family doctors say they are still wary of Labtests, but DHBs say they will demand regular test turnaround and other details of both companies, and will publish the results.
The Government says there will be a review to ensure the problems are not repeated.
Labtests has struggled since taking over from DML five weeks ago to take blood tests and report the results back to doctors quickly and reliably.
DHB spokesman Pat Snedden says giving 10% of the regional contract work to DML will take pressure off Labtests.
Mr Snedden says Labtests has improved, but the service is still seen as less safe. He says the DHBs cannot allow that and acknowledged it will take time to win back the trust of Aucklanders.