Asda, the UK’s third-largest retailer, has been singled out as the worst of the UK’s largest supermarket chains for its treatment of suppliers. The Walmart-owned supermarket chain came last in an annual survey of food suppliers compiled by Christine Tacon, the UK’s grocery code adjudicator.

About 12% of Asda’s suppliers said the retailer rarely or never complied with the Grocery Code of Practice. In the survey, food suppliers to Asda complained that the retailer had taken incorrect deductions from invoices without notice, requested lump sums to make up profit margins, and conducted “abusive” audits of suppliers’ accounts. Aldi placed highest in the survey of suppliers for the fourth consecutive year, followed by Sainsbury’s.

The survey showed that delay in payment from the large UK retailers continues to be the greatest issue for food producers, with almost a third (32%) of suppliers identifying it as a major issue. Other major concerns that remain include positioning payments and pay to stay.