Greenpeace is calling on the State Services Commission to uncover what government agencies are using private investigative company Thompson and Clark.

Commissioner Peter Hughes will announce who will lead an inquiry into Southern Response's use of Thompson and Clark where they snooped on Christchurch earthquake claimants.

Fresh links have since come to light of MBIE using Thompson and Clark for the last five years.

Greenpeace Executive Director Russel Norman has been spied on and told Mike Hosking they regularly cross the line with their approach.

"Following people home just because they are climate activists is unacceptable."

He says that the investigators also put together dossiers about who people have slept with.

Norman says while there may be room for some private investigators, Thompson and Clark act unethically.

"Thompson and Clark are quite different because they sell themselves to government agencies and companies on the basis that they attack advocacy groups, and in my view that's just poison to democracy and a free and open society."

LISTEN TO RUSSEL NORMAN TALK WITH MIKE HOSKING ABOVE