On the second anniversary of controversial police raids, political activists today told MPs a new bill allowing police greater powers to search and monitor could stifle freedom of speech.

Privacy Commissioner Marie Shroff also raised concerns and recommended a raft of beefed-up safeguards to better protect people.

Parliament's justice and electoral select committee is considering the Search and Surveillance Bill which is based on a 2007 Law Commission report and also brings together police powers which are scattered through numerous statutes.

It gives police and other law enforcement agencies increased powers such as the ability to compel people to answer questions, clone computer information and makes changes to searches and surveillance.

Several activists, arrested by police in the past, referred to the October 15, 2007 controversial police "anti-terror raids" at Ruatoki in the Eastern Bay of Plenty and Whakatane, Palmerston North, Auckland and Wellington when appearing before the committee today.

Activist Annemarie Thorby made an impassioned submission to MPs saying the new bill gave police powers to search without warrant any arrested or detained person, or if authorities had concerns about safety or felt their investigation would be compromised.

"They can just go straight in, they don't need a judge's permission," she said.

"It's a nightmare, it's bordering on a police state."

MPs emphasised the bill focused on criminals, but activists were worried it would apply to them.

Ms Thorby said the bill removed the right to silence; allowed surveillance without warrants in some circumstances; expanded excessively what information police could require a suspect to give and gave police search powers they could use for "fishing expeditions".

Privacy Commissioner Marie Shroff said law enforcement needed to be balanced against invasion of privacy and while she supported the bill, she felt better safeguards were needed.

She said people should be notified, even if it was after an investigation was completed, if they had been watched.

Warrants for searches of people's computers, including remote searching if people held information on websites, should be as specific as possible.

Another safeguard was needed around orders requiring people to produce information to authorities.

"Production orders potentially make a vast amount of information available to enforcement officers. There need to be adequate controls," she said.

"I think the confidence that your papers and your communications which now may be held electronically are secure from intrusion, is going to be an essential part of freedom of speech, liberty and people's right to feel their personal information will be kept secure."

Ms Shroff said family members' privacy should be considered. Issuing officers should be required to be precise about what would be covered by the orders, only judges should be able to issue the orders and there should be reporting for instance to Parliament on how they had been used.

"Safeguards applicable to search warrants such as notification and reporting should be applied to surveillance device warrants and production orders and we can't see why there should be lesser standards applied."

Asked about concerns raised, Justice Minister Simon Power said the bill had not raised human rights issues when vetted but he was interested to hear what the select committee decided.