State Services Commissioner Peter Hughes has directed some District Health Boards to urgently improve how they deal with requests for official information.
Public agencies received 23,733 requests in the first half of the year and responded to about 93.5 percent of them within the 20 working days deadline.
Mr Hughes said that represented a "disappointing" 1.8 percentage point decrease on the previous period.
"The latest six monthly results are a reminder that we cannot be complacent.
"I am pleased public service departments continue to improve and that more than half of the agencies included achieved 100 per cent timeliness. But we still have work to do," he said.
District Health Boards (DHBs) tended to be the worst performers.
Hutt Valley DHB responded to only 68.8 percent of its requests on time and Tairawhiti DHB to only 71.2 percent.
Counties Manakau DHB replied within deadline 77.8 percent of the time.
Auckland DHB and Bay of Plenty DHB were only slightly better, meeting the deadline with 79.7 percent and 82.9 percent of requests, respectively.
Mr Hughes has written to director-general of health Ashley Bloomfield and asked him to speak to the relevant board chairs.
"A number of DHBs are not performing as well as I expect and they need to urgently put some focus on this," he said.
"In particular, I am disappointed that the positive results achieved in the previous six months by some DHBs have not been maintained or improved... We need to see greater focus and improvement here."
Mr Hughes stressed agencies were legally required to respond to requests within deadline.
"It's not an aspirational target."
He noted the strong performance of Nelson-Marlborough, Wairarapa and Waitemata DHBs who all maintained 100 percent timeliness for the last twelve months.