The vast bulk of workplaces co-operate with visits from the Labour Inspectorate, an inspector says.

When labour inspectors turn up at work sites unannounced to check employment records and speak to staff, they will now be wearing stabproof vests.

Labour Inspectorate regional manager David Milne agreed it looked intimidating but he was adamant he and his staff were "not the Gestapo" and "not cops, they're investigators".

They were law enforcement, though.

SUPPLIED The Labour Inspectorate department sits within the Ministry of Business, Innovation and Employment.

Labour inspectors across the country work to weed out employers who do not pay or treat staff lawfully. "We want to take them out of the market."

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Workplace Relations and Safety Minister Iain Lees-Galloway has said he wants to increase funding for the labour inspectorate and double the number of inspectors by the end of the Government's term.

After 5 years in the labour inspectorate, Milne said he was no longer surprised by the scale of employee exploitation in New Zealand.

"It is a huge problem. It's latent, it's hidden, it's insidious. It's pervasive through the community. You can throw a rock at any angle."

Each region was focused on stamping out exploitation in an industry where it was known to be rampant.

SCOTT HAMMOND/STUFF Workplace Relations and Safety Minister Iain Lees-Galloway wants to double the number of labour inspectors.

Two Auckland branches each had hospitality and retail, Central had horticulture and viticulture, Wellington had agriculture and cleaning, and the South Island branch had construction and fishing.

They often took up operations with the New Zealand Police and Immigration New Zealand officials. Recently Inland Revenue officials joined inspectors on visits.

Milne likened the collaboration between agencies and departments to being a single "big regulatory shop".

All of their work was informed by tip-offs, mostly from staff making complaints to its call centre, he said. "It's not just finger in the wind type stuff."

An Auckland labour inspector, who could not be named, said employers were often shocked to see labour inspectors arrive and typically did not know who they were.

Employers complied with visiting inspectors 90 per cent of the time, she said.

She took up the job within the Ministry of Business, Innovation and Employment department three years ago after completing a university degree in geography.

She could not liken the role to any other. "It's a relatively unique job."

She was trained how to interview people, conduct investigations and take statements on the job. It was satisfying work, she said.

In addition to Lees-Galloway's desire for more labour inspectors, Police Minister Stuart Nash wants1800 more police officers before the next election.

Both recruitment targets are pending extra funding due to be announced in the Budget on Thursday.

Milne said more Government funds would allow the inspectorate to hire more inspectors and increase the scope of its work.

"We believe we would have a bigger impact than what we currently are."

The inspectorate already had a strategy to use extra resources and had applied to the Treasury for extra funding.