Key Points:

Unite Union leader Matt McCarten has joined the call for an inquiry into the activities of a police spy unit.

Earlier this week Prime Minister John Key ruled out an inquiry and said police assurances had been given to the Government that covert investigations were justified.

Today Mr McCarten released emails from police informant Rob Gilchrist to the police spy unit, detailing activities being organised by the union as part of their push to abolish youth pay rates and increase the minimum wage.

Reports of police spying on protest groups broke at the weekend.

Rochelle Rees, an animal rights and Labour Party activist, told the Sunday Star-Times she had discovered her former partner, Mr Gilchrist, had been paid by counter-terrorism police to spy on the protest groups when she helped him fix his computer.

Mr Gilchrist, heavily involved in various campaigns and protests over the last decade, was paid to pass information on the groups plans and members to the police Special Investigation Group (SIG).

Mr McCarten said today the emails he was releasing gave the lie to a police claim that only potential criminal actions by individuals were being targeted.

"A wide range of legal actions by unions, political parties and peace and justice groups came under the evil eye of the police.

"There is no evidence that the actions of Gilchrist were in any way discouraged by the police.

"We need a full public inquiry into the actions of the police spy unit whose actions have clearly gone way beyond any legal mandate," said Mr McCarten.

Green MP Keith Locke called for an inquiry when the story first broke, and yesterday his party was furious that Mr Gilchrist had infiltrated its offices and was used to report on the party's activities.

Mr Locke said there were rules about how police could act in Parliament's precincts and he would be writing to Mr Key, Police Minister Judith Collins and Police Commissioner Howard Broad with his concerns.

The SIG teams were set up in 2004 to focus on terrorism and threats to national security.

They are reported to have monitored Greenpeace, animal rights, climate change campaigners and, according to Mr McCarten, the Unite Union.