The Ministry of Health is recommending anyone in Taranaki, or who has visited recently, and who has Covid-19 symptoms to get tested for the virus.
The advice comes after two positive wastewater results were detected in the region this week.
The ministry said the results could be due to recently recovered cases continuing to shed the virus, or could signal undetected cases in the community.
"In order to determine whether there are any undetected cases the Ministry is recommending anyone in Taranaki, or who has visited recently, and who has symptoms to get tested," the ministry said.
The ministry reported three new Covid cases in managed isolation today. There are also two historical cases of the virus in MIQ.
Ten previously reported cases have now recovered, bringing the total number of active cases in New Zealand to 75.
Of the three new cases in MIQ, one arrived from the Philippines via Australia on July 11. They tested positive after a return check on day 12.
Results for further wastewater sampling were being carried out today in Taranaki and were expected back on Monday, the ministry said.
All tests of port workers and nurses have so far returned negative results.
Anyone who had returned from Australia and were now in Taranaki, but had not experienced symptoms, should also get tested, the ministry said.
Last night, the Ministry of Health said officials were investigating whether any recovered cases who live in the New Plymouth area had recently left a managed isolation facility.
Otago University epidemiologist Michael Baker said a community outbreak couldn't be ruled out but was very unlikely.
