Leading apparel brands including Gap, Adidas and H&M Hennes & Mauritz are looking at ways to reduce pollution within their supply chains following accusations that they were purchasing clothing from suppliers who illegally discharge polluted water in China.

The report, titled 'Sustainable Apparel's Critical Blind Spot' was published by Friends of Nature, the Institute of Public & Environmental Affairs (IPEA), Green Beagle, Envirofriends and Nanjing Greenstone.

H&M, Nike, Esquel, Levi Strauss & Co, Adidas, Wal-Mart, Burberry and Gap have "proactively" followed up the allegations and have established screening mechanisms. As a result, the companies have pushed more than 200 textile and leather suppliers to explain violations and their follow-up actions.

In addition, Adidas, Nike, Levi Strauss & Co and H&M have already started to extend management down to dyeing and finishing suppliers.

H&M and Esquel have started using the Pollution Map Database to screen suppliers. Adidas said it continues to search for non-compliant suppliers and push them to go through third-party audits.

Gap has also started to push suppliers to provide explanations for environmental non-compliance.

However, Polo Ralph Lauren, Tommy Hilfiger, JC Penney, Abercrombie & Fitch, Victoria's Secret and Macy's were among some of the brands to remain silent, the report found.

Meanwhile, Marks & Spencer said it the issues will be "addressed as required" in April. Two of its factories in Zhejiang have had complaints issued against them including waste gas treatment problems.

The research follows a report in April, accusing the retailers of purchasing clothing from suppliers who illegally discharge polluted water in China and listed more than 6,000 environmental violations by Chinese textile enterprises.