The Government Communications Security Bureau refuses to say whether it transmits information from American spy satellites to the United States.
Information leaked by a former US National Security Agency contractor who is now in Moscow, has suggested listening stations such as the one at Waihopai are used to collect data from American spy satellites as they fly overhead.
Green Party co-leader Russel Norman said it is impossible to know whether that includes information about New Zealanders that is also passed back to the NSA.
The GCSB said its interactions with other agencies comply with the law.
But Dr Norman said he has no faith in that statement.