Police should soon be able to install wireless cameras to spy on suspects in their homes after politicians signalled they will give new video surveillance laws the green light.

Police will be able to covertly film people for up to two months with a warrant, and three days without a warrant in "limited circumstances" under the controversial Search and Surveillance Bill, currently before the justice and electoral select committee.

Council for Civil Liberties spokesman Michael Bott says surveillance should be conducted only with a warrant and once just cause is shown. The ability to snoop on people for three days without a warrant is a "licence for a blank cheque fishing expedition", he says.

"All New Zealand citizens should be concerned police can potentially break into their house in the same way as a burglar and plant surveillance equipment and snoop on people ... and without any judicial oversight for three days.

"That's a huge increase in state power and in this age I think it's draconian and excessive."

Police spokesman Jon Neilson declined to comment on the bill as it is still before Parliament, or on police plans to make use of their new powers.

The bill is being reworked to address some fears of its opponents, who said it would give a range of state agencies – including council dog-control officers and meat inspectors – sweeping search and surveillance powers, such as the ability to search cars and install cameras and bugs on private properties.

Select committee chairman Chester Borrows says it was never Parliament's intention to bestow the powers on a wide range of agencies and blamed the confusion on poorly worded legislation.

An interim report by the select committee says it is considering several recommendations to amend the bill – including placing limits on the use of video surveillance.

It is considering whether only agencies authorised through legislative orders and considered to have the appropriate technical ability and processes should be allowed to conduct visual surveillance which requires entering private property.

Such surveillance might only be allowed for the investigation of offences punishable by seven years' imprisonment or more, or for offences under the 1983 Arms Act.

Mr Bott says the suggested limitations go some way in easing concerns about video surveillance powers but there is still a risk they could be unjustifiably extended to a raft of agencies.

"The mere fact that we almost had without public outcry the introduction of basically wholesale snooping powers given to practically every government organisation is worrying."

Police told the Economic Development Ministry in 2006, in a submission on the allocation of radio spectrum, that they hoped to use wireless broadband and remote video surveillance equipment to conduct "covert operations" within five to 10 years.

The bill also gives authorised agencies the power to access data stored on the internet and to search and copy information from computer drives.

Mr Bott says the bill will open the door to warrantless searches, which the police will be able to conduct on the mere suspicion of an imprisonable offence, and the threshold for conducting such searches should be much higher.

The public has until September 3 to make submissions on the interim report.