Hospital and school caterers are not doing enough to stop farmers from overusing antibiotics in their animals, according to campaign groups.
Such overuse raises the risk of antibiotic resistance rendering key human medicines ineffective.
Health and animal welfare campaigners analysed 10 UK caterers' policies and found a lack of a ban meant controls on antibiotics could be weak or absent.
The government, caterers and suppliers say voluntary measures are effective.
The Department for Environment, Food and Rural Affairs (Defra) points to a 55% drop in antibiotic use in food-producing animals since 2014 and an 83% decrease in the use of antibiotics most critical for human use.
Caterers who supply the public sector said they were committed to reducing unnecessary antibiotic use in animals farmed for food.
