Amazon has been ranked at the bottom of the pack in the Groceries Code Adjudicator’s (GCA) supplier compliance rankings for the third consecutive year. More than a third of suppliers said the retailer rarely or never adhered to the industry’s fair treatment rules, according to a report by The Times.

A survey by the GCA revealed that only 66% of the e-commerce giant’s grocery suppliers felt that the company follows the codes of fair treatment for suppliers within the industry.

This is a significant contrast from Lidl, with the comparable figure at 91%, while all other retailers surveyed had an average of 93%.

More than one-quarter (34%) of Amazon suppliers responded that Amazon never or rarely adhered to the code, compared to under 9% of suppliers at Lidl. Waitrose emerged on top of the ranking, with a comparable figure of just 2.25%.

Additionally, Amazon’s suppliers were more likely to have reported issues within the past year, with 13% having raised concerns with the online giant. This figure is far ahead of the second worst-ranked retailer in the category, Sainsbury’s, at 3%.

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The GCA is an adjudicator founded in 2013 to maintain the Groceries Code and has the power to fine major retailers up to 1% of their UK turnover.

However, Amazon highlighted that it has made progress, with a 19% year-on-year increase in the percentage of suppliers stating it adheres to rules.

Mark White, GCA’s chief executive, said that the results indicated improvement in the treatment of suppliers; however, he warned retailers to change accordingly based on the findings.

Amazon remained insistent that it was improving its supplier treatment by making changes to its dispute resolution, payment procedures and account management.

The news comes on the heels of an investigation launched by the GCA last week, alleging that Amazon breached its rules on suppliers’ payments.