UK supermarkets are not doing enough to make sure suppliers are using antibiotics responsibly, new research has found.

It comes despite new regulations which were rolled out in the UK this year to limit the use of antibiotics in farming, with British farmers no longer covered by EU rules.

The law states that antibiotics should not be used to compensate for inadequate animal husbandry or poor hygiene.

An assessment by the Alliance to Save Our Antibiotics (ASOA) ranked supermarkets based on criteria including if it has a target on cutting antibiotic use, what policies it has in place to ensure antibiotics are only used when necessary, what produce these policies cover, and whether it monitors antibiotic use in its supply chain, The Guardian reported.

None of the 10 supermarkets examined, including Aldi, Asda, Co-op, Iceland, Lidl, M&S, Morrisons, Sainsbury’s, Tesco and Waitrose, have published data in full on antibiotics detailing use of the medicines by each farm supplier, as most of their policies only cover their own-label products.

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However, M&S was the most highly ranked supermarket, having received 10 green ticks of a total 12 and two amber, with green representing good practice, amber for criteria has been partly met, and red for poor.

M&S, alongside Morrisons, were also the only supermarkets to fully ban colistin, which the World Health Organization has said should be used as a last resort drug for human use.

Meanwhile, Waitrose and Tesco came in at joint second place, both having received the same ranking, with six green ticks, five amber and one red for not publishing antibiotic-usage data by farm system.

An Iceland spokesperson told The Guardian that it publishes its policies directly to its suppliers and not publicly, as it disputed the findings.

They added that the frozen food retailer’s policy restricts it from using highest priority critically important antibiotics, such as colistin, and that it follows EU and UK regulations.

ASOA policy and science manager Cóilín Nunan told the title: “It is no longer legal to use antibiotics to prop up farming methods that are causing animals to fall sick. So to avoid misusing antibiotics, and to keep animals healthy, supermarkets must now take strong and urgent action to improve animal husbandry and welfare.”