Privacy Commissioner John Edwards said a provision to allow video surveillance of a private property for up to 12 months with a warrant was "quite extraordinary and qualitatively different" to current powers.
"It is far more than going into a house and uplifting a series of documents or property. It is far more intrusive and comprehensive than dipping in and out of a telephone communication or checking on someone's internet access.
"It is there, it is on all the time, it is recording matters of considerable intimate and private behaviour."
Mr Edwards recommended that the default period for surveillance should be cut to three months.
The fast-tracking of the bill was as controversial as its contents. The window for public submissions was two days, and the committee was required to report back on Tuesday. It will be passed before the end of the year. The use of urgency was described as a "disgrace" by National's coalition partner the Maori Party, and was slammed by most submitters.
The Law Society said rushed law-making usually resulted in bad law-making: "It is highly undesirable to pass legislation of this nature under urgency."
Chief Human Rights Commissioner David Rutherford said the law changes alone were not enough to stamp out extremism.