Secrecy remains over evidence of serious misconduct from Ministry of Primary Industries and SIS staff in dealing with security firm Thompson and Clark.

All government agencies will be scrutinised as part of an expanded probe by the State Services Commission into the use of Thompson and Clark.

Ministry for Primary Industries said it uncovered potentially serious misconduct by some former staff members, and the Security Intelligence Service (SIS) has launched an internal investigation after evidence of its staff being unprofessional and biased towards the firm.

However, the ministry refused to release that evidence and State Services Minister Chris Hipkins would not comment on it.

"I have some insight into that but that's a matter for MPI to comment on I'm not commenting on the specifics of those investigations," Mr Hipkins said.

The ministry was also keeping the evidence of serious staff misconduct under wraps, saying it was being investigated.

Ministers also expressed their concern over the allegations but would not expand on the details of the investigation or the claims.

Photo: RNZ / Rebekah Parsons-King

SIS Director General Rebecca Kitteridge would not comment, while Damien O'Connor, one of the Ministers in charge of MPI, said he did not know much.

"I don't know too many of the details other than I welcome an investigation," Mr O'Connor said.

Deputy prime minister Winston Peters was also concerned, but like the other ministers emphasised the investigation.

"I have to wait the outcome of the commissioners inquiry and he's got a very good team there with investigators so let's see what happens," Mr Peters said.

Minister for GCSB and SIS Andrew Little said he had not checked if his ministries were above board.

"I'm not aware of any other departments under my responsibility, though I have to say I haven't actively inquired," Mr Little said.

Mr Hipkins said Prime Minister Jacinda Ardern made it clear the use of third-party firms needed to stop.

Government departments have a degree of autonomy under the State Sector Act and stopping agencies from using a particular firm required changes to the contracting rules, he said.

"In order to prevent government agencies from using a particular supplier of any sort, that would require a law change," he said.

Mr Hipkins said it had become clear Thompson and Clark had a much wider relationship with the public sector than the government was aware of.

RNZ has been told no government agency has contracted Thompson and Clark since the Labour-led government took power.

'Clear and strong' public interest

In a statement to Checkpoint tonight, State Services Commissioner Peter Hughes said the public interest was "clear and strong" and that was why he had ordered an investigation across the whole of the state services.

"We are now in the inquiry process, using my powers under the State Sector Act. These are significant. This is a serious process with potentially serious consequences for the individuals involved.

"I am determined to get answers to the questions that have been raised - but I am not going to compromise the inquiry process in any way by talking now about matters that have yet to be investigated.

"At the end of this, as I always do, I will front up to the media and release all the information relevant to the inquiry. Along with the investigators and relevant chief executives, we will answer all questions put to me and them. In the meantime, we need to let my inquiry get to the bottom of this."

How the investigation unfolded

Newshub broke the story of Southern Response earthquake claimants being spied on by Thompson and Clark, which is what started the inquiry.

The inquiry was then expanded to include the Ministry of Business, Innovation and Employment after TVNZ reported Thompson and Clark spied on Greenpeace.

The inquiry was now expanded to all government agencies after RNZ uncovered evidence of unprofessional conduct at the Ministry of Primary Industries and the SIS.

Private companies demand reassurances

The Thompson and Clark scandal was now prompting private companies to demand reassurances.

Animal welfare charity SAFE chief executive Deborah Ashton wrote a letter asking whether any information about Farmwatch or SAFE has been provided to Thompson and Clark, either directly or indirectly at MPI.

An animal welfare activist was alarmed authorities may have been communicating with a controversial private investigator that targeted him in the past.

Farmwatch's John Darroch said he was warned off targeting pig farmers in the past by an investigator hired by Thompson and Clark.

"We've also asked for assurances about how information which we provide to MPI will be protected in the future so it can't be given to people who shouldn't have access to it," Mr Darroch said.

He said the ministry was supposed to be looking after animal welfare, not potentially helping to undermine groups like his.