National Party Leader John Key says the Opposition has been vindicated for demanding further inquiries into the activities of Taito Phillip Field despite Helen Clark's protestations.

"Noel Ingram QC recommended that authorities with more powers may want to look into the Field case, something that the Prime Minister rejected and said was a waste of time and energy.

"National has always maintained that the terms of reference set by Helen Clark into the Field saga were too narrow, and as a result the inquiry was unable to fully explore all the allegations."

Mr Key says that at that time, Helen Clark was cynically trying to protect her narrow parliamentary majority.

"Helen Clark knew that the Noel Ingram inquiry lacked sufficient teeth to get to the bottom of what went on. And she was happy to leave it at that. Yet what we have today is unprecedented action against a former Minister in her Government."