Key Points:

The police-paid spy Rob Gilchrist passed officers information about union pickets, student demonstrations, and a pepper-sprayed protester who was preparing a case against them.

New Zealand's biggest union, the Engineering, Printing and Manufacturing Union, and the Unite union last night called for a Commission of Inquiry into the police's Special Investigation Group that Mr Gilchrist worked for.

It followed the release of further emails that Mr Gilchrist forwarded to his police handler which contradict Police Commissioner Howard Broad's assurances that the SIG's investigation of activist groups only targeted individuals.

The emails, seen by the Herald, refer to plans by the eight union groups.

They discuss protests about youth rates outside fast-food outlets like McDonald's, a picket schedule during the Progressive Enterprises lockout and meetings about National's "fire-without-recourse" bill.

The SIG received information about the EPMU, the Maritime Union, National Distribution Union, Unite, National Union of Public Employees, Youth Union Movement and Council of Trade Unions.

Mr Gilchrist gave officers information about planned protests against fees by student groups like the Victoria University of Wellington Students' Association.

Mr Gilchrist also forwarded an email from well-known activist Simon Oosterman, asking for witnesses to his pepper-spraying at a GE Free protest because he was preparing a case against police.

Mr Gilchrist was an activist himself, but was discovered to be working for the police Special Investigations Group by his ex-girlfriend Rochelle Rees.

The SIG was set up to monitor terrorism and threats to national security.

EPMU president Andrew Little said the SIG "has gone well outside its mandate" and an inquiry was needed to establish whether Mr Gilchrist was "acting as a police-sponsored unguided missile or whether something more sinister was afoot".

Mr Little did not believe the Independent Police Conduct Authority would have sufficient powers to investigate, preferring a Commission of Inquiry because it could compel witnesses such as senior police intelligence officers.

The story so far:

Police-paid spy Rob Gilchrist has claimed he was working for a "higher cause" while infiltrating activist groups, but won't reveal what it is.

His ex-girlfriend Rochelle Rees said she had spoken to Mr Gilchrist since exposing him and he said he loved her but was doing it for the higher cause.

Ms Rees said police had been putting $600 cash a week into the bank account of Mr Gilchrist's company "Urban Camouflage".

Ms Rees said Mr Gilchrist claimed he was in the SAS, with a collection of the unit's memorabilia. But an email she discovered showed him writing to a unit reunion, saying: "I was just a low-level grunt in the territorials."