The organisation has also issued a warning to H&M for the same reason and has contacted the Sustainable Apparel Coalition (SAC), which operates the Higg MSI.

The Norwegian Consumer Agency concludes that the tool is “not sufficient as a basis for the environmental claims they have used in marketing”.

Director Trond Rønningen said: “The textile industry must be aware that marketing of environmental benefits, which is based on the industry tool MSI, can easily be considered misleading and illegal marketing.”

In the case of Norrøna, the company used figures from the Higg MSI to gives the impression that because the t-shirt is produced from organic cotton rather than “ordinary” cotton, the t-shirt has significantly less environmental impact, the agency said, but there is no substantial evidence for this claim.

This, the organisation said, it is because the MSI does not document the environmental properties of a specific product. The Norwegian Consumer Agency also pointed out that the research data the Higg MSI is based on is partly outdated and not intended for such comparisons.

In the case of H&M, the company has reportedly either taken into use or planned to use the Higg MSI to communicate the environmental benefits of its products to consumers and the agency has warned the company in advance of the potential for any such marketing to be misleading and illegal.

Finally, the Norwegian Consumer Agency has sent a letter to the SAC informing it of its co-responsibility if its members use the Higg MSI as a basis for illegal environmental claims in their marketing. In order for SAC to avoid liability, the organisation has encouraged the SAC to stipulate that it is not permitted for companies using the Higg MSI to use the tool for marketing environmental benefits to consumers.

The Higg MSI was recently criticised in a New York Times article by climate reporter Hiroko Tabuchi.