Controversial security firm Thompson and Clark uses secret chat channels to communicate with government departments, and share information about members of the public it's monitoring for those departments.

Documents released to Checkpoint under the Official Information Act show the Department of Conservation has used Thompson and Clark to monitor anti-1080 activists since October 2016.

Photo: SUPPLIED

Intelligence is shared with DOC staff via multiple private channels on messaging app Slack. There is also a weekly phone briefing involving senior staff from both organisations.

But DOC is refusing to release any information or communication from any of the channels.

Listen ( duration 5 ′ : 02 ″ )

Listen Download: Ogg | MP3

"It is deemed that providing such information may prevent supply of such information in the future and therefore jeopardise the safety of our staff," DOC's director of safety, Harry Maher, said in an OIA response.

Thompson and Clark director Gavin Clark declined to comment when asked if his firm had threatened to cancel DOC's contract if the information was released.

DOC has spent $103,187 excluding GST with Thompson and Clark since 2015.

It pays $3737 per month for the intelligence Thompson and Clark provides about anti-1080 activists - called a "risk assessment package", it's part of what Thompson and Clark calls its Fusion Centre.

Mr Maher said DOC staff could be harassed if the intelligence from those channels is released, "and it also runs the risk of driving some of the conversations underground", he said.

One example is a private, hidden channel set up at the end of October last year after the illegal release of native-plant-eating Sika deer in Taranaki by 1080 protesters.

The channel was only accessible by three Thompson and Clark staff and three DOC staff, and DOC specifically requested the information shared in it not be included in its monthly situation report.

Several other government departments are signed up to similar packages, according to documents released under the Official Information Act, but the list was redacted.

The use of secret chat channels comes as the State Services Commission investigates allegations state insurer Southern Response hired Thompson and Clark to spy on Christchurch earthquake claimants, and whether the Ministry of Business Innovation and Employment's relationship with the firm breached "Standards of Integrity and Conduct".

Greenpeace has also alleged it was spied on by Thompson and Clark, and Prime Minister Jacinda Ardern last month warned government departments against using the firm to spy on the public: "Their behaviour around spying and so on is totally inappropriate," she said.

But Mr Maher said DOC "never asked [Thompson and Clark] to do any surveillance" and the firm has "assured [DOC] they haven't" spied on anyone.

He said the intelligence gathering was necessary because of threats made by anti-1080 activists who in some cases had threatened to shoot down helicopters.

"They've threatened to kill our staff and their families, we've had physical confrontation, and we've had instances of tampering with vehicles, loosening wheel nuts.

"So we needed a specialist security company to help us with that because we just don't have the resources or expertise," Mr Maher said.

Threats are collated and assessed by Thompson and Clark as to whether they could likely be carried out. If the risk is high they are forwarded onto police.

Thompson and Clark director Gavin Clark has not commented publicly about the SSC investigation but emailed clients last month, including DOC, saying he "strongly refutes the allegations made".