Asda is asking its dairy farmers to sign up to a major carbon reduction programme in an effort to make its milk more environmentally friendly.

In what is thought to be the first such scheme for farmers, the multiple has drawn up targets for a 10% cut over three years in farm emissions of the most potent greenhouse gases: methane, nitrous oxide and carbon dioxide.

Though Asda had no plans for a carbon label on pack, the initiative would help improve milk's green credentials, said sustainable sourcing manager Chris Brown. "We are taking a lead on this because the environment is important to Asda and its customers. We want to show our low prices don't damage the environment," he said. "We don't want consumers to switch from dairy because they think it makes environmental sense to do so," he added.

Participating farmers will receive a 'traffic light' assessment of their emissions, with red indicating higher than average and green indicating lower. They will also get expert advice and training to help them improve their performance.

The model has already been piloted on 10 farms in its supply group within the Arla Foods Milk Partnership. The most efficient farmers produced about 700g of CO2 equivalent per litre of milk, with the average producing 900g.

"The close relationship with our farmers allows us to work through the chain to make improvements," said Brown, who insisted that Asda had no plans to introduce price premiums or penalties for those with particularly low or high carbon emissions.

Sainsbury's, Waitrose and Marks & Spencer are also working on carbon reduction programmes, through Dairy Crest's farm assurance auditors White Gold. A spokesman for Dairy Crest said it was close to piloting the scheme.