The Green Party says the latest inquiry into the government's spy agency shows up what it calls the Prime Minister's slack oversight.
The spy watchdog is investigating claims the Government Communications Security Bureau (GCSB) helped Trade Minister Tim Groser's 2013 bid to head the World Trade Organisation.
Inspector-General of Intelligence and Security Cheryl Gwyn said she would be looking into how the GCSB determined what intelligence activity to undertake, and how that was regulated.
Green Party co-leader Metiria Turei said it was unprecedented for a government agency to be investigated by a watchdog three times in nine months.
She said it was further evidence John Key's hands were off the wheel in his department.
But the Minister Responsible for the GCSB, Chris Finlayson, told Morning Report he was not concerned at the number of investigations into the agency.
"We extended the jurisdiction of the Inspector-General to have what are called de novo or own motion inquiries so, surprise, surprise, on occasion she's having them," he said.
"I can tell you there'll be a lot more as well and I'm perfectly relaxed about it."
He said the fact that complaints were made, or inquiries were undertaken, did not mean the allegations were correct.