SPY VS SPY: Kim Dotcom along with a host of other speakers fronts a large audience at the Mount Albert Memorial Hall in Auckland discussing the issues surrounding the new GCSB Bill soon to be introduced in Parliament.

New Zealander of the year Dame Anne Salmond has denounced politicians and said they "need to grow a backbone" rather than considering passing a spy bill which she says has been "universally condemned" by the public.

Salmond was speaking to more than 400 people at a public meeting in Mt Albert, Auckland tonight in opposition to the Government Communications Security Bureau Amendment Bill. Dr Rodney Harrison QC, Megaupload founder Kim Dotcom, who was illegally spied on, and Thomas Beagle a civil liberties expert also spoke.

The meeting preceded marches organised against the bill.

Dame Anne said New Zealanders ought to feel "very concerned" about the bill.

"This agency... is surrounded by scandal. It has been accused of carrying out illegal surveillance on New Zealand citizens. This bill allows the GSCB to illegally spy on New Zealanders.

"This bill is in breach of the Bill of Rights... and despite this it has been dealt with under urgency.

"All of the authorities have looked at this carefully and have argued this bill be shelved."

Dame Anne said the bill would be an "absolute indictment" on the government if it was passed.

Harrison, who said he was speaking in a personal capacity and not on behalf of the New Zealand Law Society, said he agreed that MPs needed to "grow some backbone".

"If you are going to increase the powers of the GCSB you have to apply much greater scrutiny because most of what they do will never come to public attention.

"Legislation dealing with their powers has to be carefully and tightly drawn. This legislation is not. It is hopelessly broad."

Harrison said "most of us" were "totally ignorant about the methods that are being used by the GCSB".

"History tells us that once enforcement agencies and spy agencies are clothed with power it is never taken away from them it is only ever increased.

"This is ill conceived and downright dangerous legislation... our democracy is seriously in danger."

Dotcom, who has all but become the face of the concerns over the GCSB bill, said he was a "living, breathing example of why the GCSB must not be given greater powers and limited accountability".

"What can New Zealanders expect from the GCSB when rules are broken without consequences? You can expect the rule breaking to continue.

"There is a cultural problem within the GCSB. They appear to view themselves as above the law. The new GCSB bill is like raising the speed limit after you have been given a speeding ticket.

"If we do not seize this unique moment to reform our spy law and practises we will live to regret it... I think that [this bill] is more dangerous to New Zealanders than any national security threat."

Beagle outlined what mass data collection would mean and said mass surveillance is what happened when a government was "scared of its people".

"We shouldn't be giving the government these tools to oppress us."