The National Party is calling for a broader investigation into whether the government's most senior ministers orchestrated a smear campaign against the opposition over budget hacking claims.
Police were called in by the Treasury to investigate how National obtained secret Budget details, but quickly concluded nothing illegal had happened.
The Minister responsible for the GCSB, Andrew Little, received a call from the spy agency's head Andrew Hampton to say no hack had occurred, but he is not willing to say when he passed that on to Finance Minister Grant Robertson.
The State Services Commission is investigating the Treasury's actions but it cannot legally look at the role government ministers played in the aftermath.
RNZ political reporter Jo Moir has the story.
