Ads for Calvin Klein, Adidas and Uniqlo promoting “recycled” clothing and shoes have been banned by the UK watchdog after the advertisers were unable to prove their green claims.

Each of the fashion companies ran paid-for Google ads, with Adidas promoting “recycled running shoes”, Calvin Klein “recycled” tops for women, and Uniqlo advertised fleece coats and jackets made from “recycled materials”.

The Advertising Standards Authority (ASA) investigated the ads, challenging the companies to substantiate the claims made.

Adidas said it did not have a recycled running shoe range but certain products across its collections might incorporate recycled materials, and that it held internal product documentation to confirm its claims.

Calvin Klein said certain products in its women’s T-shirts and tops range included “environmentally preferred materials” – including recycled, organic and other materials – and that it would not be reasonable for consumers to interpret its ad as meaning the claims applied to the entire range.

Uniqlo said that consumers were likely to understand from its ad that the products were made to a “meaningful extent” from recycled materials, and that its claims were supported by an international certification scheme.

However, the ASA said that, in each case, without further clarification the use of the term “recycled” would lead consumers to believe that the products were all made entirely from recycled materials.

It added that if such absolute environmental claims are made in ads then they “must be supported by a high level of substantiation”.

“It’s important that people can trust the environmental claims they see in ads,” said the ASA director of complaints and investigations, Miles Lockwood. “When absolute terms like ‘recycled’ are used, the basis of those claims should be clearly explained and properly supported by evidence. Without that, there’s a risk that people could be misled. We’ll be continuing to monitor ads making green claims, taking action where we do see ads breaking the rules, whilst also supporting advertisers with advice and guidance to help them get it right.”

The latest bans handed down by the advertising regulator form part of a wider investigation into environmental claims in ads in the retail fashion sector. In December, the ASA banned ads for Nike, Superdry and Lacoste for misleading consumers about the environmental sustainability credentials of their products.