Privacy Commissioner Marie Shroff is calling for a delay in the passage of the GCSB legislation.
She wants more time to be given to considering oversight.
While she has no mandate to comment on the collection and use of data by intelligence agencies, she has raised questions about it in a submission on the proposed law.
"Effective oversight is required to ensure that it is collected and used appropriately, not as the tool of mass surveillance that it has the capacity to be, if unchecked."
She referred to leaks by former United States National Security Agency contractor Edward Snowden about the widespread collection of data and British intelligence spying on G20 delegates.
Fallout from those revelations would not be answered for some time.
"There is, therefore, good reason to postpone consideration of this bill at least for a short time, to enable us to develop a clearer perspective on what powers New Zealand intelligence agencies should have to perform their functions."
The Government Communications Security Bureau and Related Legislation Amendment Bill expands the legal powers of New Zealand's foreign intelligence agency to spy on New Zealanders and prevent cyber threats to important private sector infrastructure as well as government communications.
The Human Rights Commission has given the Prime Minister a report setting out its concerns about the bill.
It said that citizens were entitled to know if mass surveillance of data relating to them was being collected by New Zealand's intelligence agencies or its international intelligence partners and for what purpose.
Ms Shroff's criticisms were made in a submission to the intelligence and security committee considering the bill.
She acknowledges that the bill aims to extend the oversight of the Inspector-General of Intelligence and Security but says that would be dependent on resourcing.
"Failure to resource the IGIS properly would result in a failure of the principal oversight mechanism that this bill creates."
But she also said it was not clear whether the oversight model was the best for modern intelligence agencies and it would be worth considering other models in more detail.
The bill allows for the Inspector-General to have a deputy.
Prime Minister John Key has also accepted a proposed panel of two people, who the Inspector-General would use as a sounding board.
Ms Shroff said an example of personal information that could raise serious concerns was metadata in the form of telecommunications traffic information.
"Metadata is not necessarily innocuous," said Ms Shroff. "It can provide a detailed map of a person's life - such as tracking their location, contacts and interests. That is why it is valuable in the intelligence area."