Serious breaches of employment standards among contractors operating in Marlborough vineyards are threatening the wine industry's reputation, says a labour inspector.
The Ministry of Business, Innovation and Employment says a joint operation involving labour, immigration and tax officials found problems with several contractors visited.
Labour Inspectorate regional manager Kevin Finnegan said inspectors believed Double Seven Services and Vine Strength had breached minimum wage and record-keeping requirements.
Mr Finnegan said better due diligence was needed from the industry.
"They put their brand and their sales in danger. Their overseas customers are going to demand ethical standards, and employment rights are a part of that."
Mr Finnegan said the problem was highlighted in Marlborough because it was the biggest wine region.
He said further action was likely against the two contractors.