Norway's consumer watchdog has criticised fast-fashion chain H&M for misleading marketing of its "sustainable" Conscious collection.

The Norwegian Consumer Authority (CA) has said that the Swedish clothing retailer provides "insufficient" information about the sustainable nature of its "sustainable style" collection.

CA director, Elisabeth Lier Haugseth, warned consumers that they may be being misled by "greenwashing" statements featured in companies' marketing strategies.

"Based on the Norwegian website of H&M we found that the information given regarding sustainability was not sufficient, especially given that the Conscious Collection is advertised as a collection with environmental benefits," Haugseth told Dezeen.

The term "greenwashing" applies to instances where unsubstantiated or misleading claims are made about the environmental benefits of a product, service, technology or company.

These claims can consequently make the firm appear to be more environmentally friendly than it truly is.

In April, H&M launched its latest Conscious collection, claiming that every piece in the collection is made from a sustainably sourced material, such as 100 per cent organic cotton, Tencel or recycled polyester.

However, as Haugseth told Dezeen, the information offered to consumers by H&M regarding the sustainability of their Conscious collections was "not sufficient".

She argued that the fashion retailer makes general claims in the marketing of its products when referring to their "sustainable" aspects.

"The information on the collection was general and did not specify the actual environmental benefit of each garment sufficiently, for example the amount of recycled material for each garment," Haugseth said.

"We consider this information important for the consumer as the clothing is marketed as being less harmful to the environment," Haugseth added.

"For instance, the consumers should know if a garment is based on five per cent recycled material or 60 per cent."

Alongside the Conscious collection, the brand also launched a premium Conscious Exclusive collection. It claims to "explore the healing power of nature, while also embracing innovation with sustainable materials and processes for a more sustainable fashion future".

H&M touted its use of new plant-based sustainable materials in the premium collection, to create "high-performing, beautiful and fashionable" statement pieces.

These materials include Piñatex, a natural leather alternative made from pineapple leaves, a plant-based flexible foam made using algae biomass called Bloom Foam, and Orange Fiber, a sustainable silk-like fabric made from citrus juice by-products.

According to the CA's legal guidelines on marketing, a commercial practice is considered misleading if it "contains false information and is therefore untruthful".

It also condemns marketing likely to deceive consumers on the nature of a product, causing them to make "an economic decision that they would not otherwise have made".

The CA concluded that H&M's portrayal of the sustainability of its collection breaches Norwegian marketing laws.

In addition to glazing over specific information about the clothing's benefits, composition and specifications, the brand was also using promotional statements that could potentially mislead buyers.

Haugseth is encouraging companies to be more specific when advertising sustainability.

"The focus should be on what your company is actually doing to be more sustainable, and refrain from using general terms such as 'sustainable', 'environmentally friendly' and 'green'," Haugseth explained.

In response to the claims, the fashion brand told Dezeen that they are in contact with the CA about how they can make their Conscious collection marketing more "precise".

"We are pleased that the Norwegian Consumer Authority puts light on marketing of sustainable alternatives," said a spokesperson for H&M.

"We have a good dialogue with them regarding how we can become even better at communicating the extensive work we do. We have had a very good meeting with them and we are glad that they want to work with us and help us provide correct and clear information to consumers."

"Please note that what the Norwegian Consumer Authority is looking into whether the information we're providing connected to our Conscious-products is precise enough, they're not looking into whether our products are sustainable or not," they added.

Brands are increasingly responding to the growing interest in fashion's environmental impact with sustainable claims, whether true or not.

Spanish fashion retailer Zara recently announced that it will only use cotton, linen and polyester that is "organic, more sustainable or recycled" by 2025.

"Giving consumers the opportunity to make environmentally conscious choices is commendable, but companies need to make sure not to mislead," said Haugseth.

"And as a consumer, you need to be aware that the 'green' product you have acquired may not be as good for the environment as you got the impression of," she added.

British fashion designer Stella McCartney shared a similar opinion in an interview with Dezeen last year, where she stressed the need to impose new laws on designers, who currently "aren't taking responsibility".