The body said it has written to the firms outlining its concerns “and will use its information-gathering powers to obtain evidence to progress its investigation”.

Not that there’s concrete evidence so far of fake or exaggerated claims. And ASOS was quick to respond to news of the investigation saying the same day it “will co-operate… and is committed to playing its part in making fashion more sustainable, including providing clear and accurate information about its products.” 

It added: “ASOS does not propose to comment on the investigation further at this stage”.

The CMA said its latest move is part of its ongoing investigation into potential greenwashing and follows “concerns around the way the firms’ products are being marketed to customers as eco-friendly”.

In January, the body turned its eye to the “£54 billion sales a year fashion sector” and its initial review identified “concerns around potentially misleading green claims”. 

These included a number of companies creating the impression that their products were ‘sustainable’ or better for the environment. Specifically, these were “making broad claims” about the use of recycled materials in new clothing “with little to no information about the basis for those claims or exactly which products they related to”.

In a bid “to get to the bottom of its concerns” the CMA will review whether “the statements and language used by the businesses are too broad and vague, and may create the impression that clothing collections” (such as the ‘Responsible edit’ from ASOS, Boohoo’s current ‘Ready for the Future’ range, and ‘George for Good’) are more environmentally sustainable than they actually are.

Other areas will include whether the criteria used by some of these businesses to decide which products to include in these collections may be lower than customers might reasonably expect from their descriptions and overall presentation – for example, some products may contain as little as 20% recycled fabric. The CMA said some items have been included in these collections when they do not meet the criteria.

The CMA also has worries over a lack of information provided to customers about products included in any of the companies’ eco ranges, such as missing information about what the fabric is made from.

Cardell said: “People who want to ‘buy green’ should be able to do so confident that they aren’t being misled. Eco-friendly and sustainable products can play a role in tackling climate change, but only if they are genuine.”

She added: “We’ll be scrutinising green claims from ASOS, Boohoo and George at Asda to see if they stack up. This is just the start of our work in this sector and all fashion companies should take note: look at your own practices and make sure they are in line with the law.”