Steel & Tube Holdings is facing 29 court charges of making false and misleading representations about a steel mesh product.
The Commerce Commission has confirmed it filed the charges in the Auckland District Court under the Fair Trading Act, accusing of making misleading representations on the mesh known as SE62, saying it was 500E grade steel over a four-year period up to April last year.
The mesh is usually used for reinforcing concrete floors and driveways.
Steel & Tube has been cooperating with the commission throughout the investigation and is working with the regulator to reach an appropriate resolution of the charges, the Lower Hutt-based company said in a statement to the stock exchange.
The regulator started its investigation in August 2015 after a complaint was laid about the mesh not meeting New Zealand standards.
The charges allege Steel & Tube made misleading representations on their batch tags, batch test certificates, advertising collateral and website that SE62 was 500E grade steel.
The charges also allege that false and misleading representations were made that SE62 steel mesh had been independently tested and certified. This included using the logo of an independent testing laboratory on SE62 test certificates.
The commission said earlier this year it filed charges against two companies, Timber King and NZ Steel Distributor, over false and misleading claims. They pleaded guilty and would be sentenced in August.
Steel & Tube has admitted selling "many thousands of sheets" of earthquake reinforcing mesh incorrectly labelled as being independently certified after it used the logo of accredited independent testing laboratory Holmes Solutions.
Steel & Tube's in-house laboratory, not independently accredited, had been used to test the mesh. Steel & Tube on Wednesday said it continued to stand behind its products, and noted that since April 2016 all of its seismic mesh has been tested externally by accredited laboratories.
The commission has previously said that misrepresenting a product as complying with the standard when it doesn't is a breach of the act for which companies can be fined up to $600,000 per offence.