The Security Intelligence Service says it has found a person in New Zealand who is working for a foreign state's intelligence services.
In its annual report, the SIS says the individual is a New Zealand citizen, but did not specify which country they are working for.
It says the person is almost certainly collecting intelligence against New Zealand-based people, who are viewed as dissidents by the foreign state's government.
"The target of our investigation uses overt and covert means to collect identifying information about these individuals and pass it to the foreign state's embassy in New Zealand," the report says.
The SIS says it is exploring its options to mitigate the threat.