"The Inspector-General has found that there were 'arguably' no breaches in the 88 cases involving New Zealanders.
"Well that finding doesn't exactly inspire us with confidence. In fact, it doesn't tell whether the spying was legal or illegal - all it says is that the Inspector-General can make an argument that it's legal."
Mr Shearer repeated his call for a full independent inquiry.
Mr Fletcher said the Inspector-General found that all of the cases were based on serious issues including potential weapons of mass destruction development, people smuggling, foreign espionage in New Zealand and drug smuggling.
Of the 88 individuals concerned, 15 cases which related to 22 individuals did not have any information intercepted by GCSB.
In four other cases in which the agency helped with the execution of warrants. Mr Neazor found that there were "arguably" no breaches.
New legislation which was designed to clarify the intelligence agency's role was passed under urgency earlier this month.
Green Party leader Russel Norman said the Government Communications Security Bureau and Related Legislation Amendment Bill should be put on hold until an independent inquiry could be held into the agency's spying on New Zealanders.
"A law change should be the last step in the process, not the first.
"New Zealanders need to be assured that the GCSB is behaving within the law and acting ethically before the laws governing our spies are changed."
Mr Neazor's report recommended more precise legislation and some improvement in the GCSB's paperwork.