Labour leader Andrew Little says he is more assured about the activities of the GCSB than he was a week ago, but he said Prime Minister John Key and the minister responsible for the spy agencies, Chris Finlayson, had a duty to explain to the public what was and wasn't happening.
Mr Little was critical last week of suggestions that the GCSB, the Government Communications Security Bureau, was undertaking mass collection of communications in the Pacific to pass on to the United States' National Security Agency, claims based on documents taken by Edward Snowden from the NSA.
"From the public session I take a greater level of assurance than I had perhaps a week ago," Mr Little told the Herald.
But he said questions remained "and I still maintain that it is for political masters of those agencies to be accountable to the public about what is and isn't happening".