Opposition leaders say New Zealand's involvement in the international "Five Eyes" spying network should be included in an inquiry into intelligence agencies.
Labour leader David Shearer and Green co-leader Russel Norman said too little was known about what benefit New Zealand got out of the relationship.
It also brought from Dr Norman comparisons to New Zealand's rejection of nuclear weapons in the 1980s - a step which saw the country frozen out of friendly relations with the United States for 25 years.
The call comes after a week of international suspicion over spying by the United States' National Security Agency, a sister agency to New Zealand's GCSB in the Five Eyes network. NSA whistleblower Edward Snowden claimed the agency used data from Apple, Facebook, Google, Yahoo and other tech giants to spy on billions of people.
Mr Shearer pledged to hold an inquiry into the intelligence services if the party won power next year. He said it was an important step towards improving oversight and would include the Five Eyes network.
"We have to look at that. The question is always - what is the balance? Have we got the balance right between privacy and security."
He said the revelations last week raised questions about the security of New Zealanders' information. "What we want to know is how far do those trade offs go with New Zealand? It is sovereignty, privacy of [the] individual balanced against what value we get out of what intelligence we have and what we get out of it."
Asked if he trusted the United States to look after New Zealand's data, he said he didn't know enough to make that judgment. "Let's see what we're giving up. Let's see what we're getting out of it."
Dr Norman said he also wanted the inquiry to include the Five Eyes network. "I think we need to look at the relationship in an honest way and make some kind of assessment if it is in New Zealand's's national interest to have that relationship. If it's not, you make a rational decision as a country not to continue the relationship.
"Are we willing to make independent decisions as a country that some of our older friends might not like? It is about our own independence and sovereignty."
Dr Norman said New Zealand made the decision to reject nuclear weapons in the 1980s and the decision-making had many parallels to the trade-offs around intelligence sharing and Five Eyes.
"China would view the Five Eyes network with some concern," Mr Norman said. "There is no doubt they would view Five Eyes as an impediment to a better relationship with New Zealand."
A spokeswoman for the Prime Minister said: "It is the Prime Minister's view that New Zealand's relationships with its partners are of overwhelming benefit to New Zealand's national security."