Supermarkets are out and proud about their commitment to the environment. Is this because they are pre-empting punitive government policies, responding to a shift in public opinion or simply looking out for the bottom line? Catherine Sleep investigates.

We have recently seen a string of public declarations and initiatives from UK retailers demonstrating their active commitment to the environment. Tesco promised to cut emissions from its distribution lorries; Morrisons launched a bioethanol fuel pump; and most significantly of all, Asda has pledged to stop sending waste to landfill sites by 2010.

While most retailers have been looking at their impact on the environment for some time as part of their Corporate Social Responsibility (CSR) activities, they have recently been given added stimulus by the government. Both the green platform chosen by opposition party leader David Cameron and the recent appointment of David Milliband as environment secretary have helped focus corporate minds on their environmental responsibilities. Just two months into the job, Milliband seems determined to justify his reputation as a hard-hitter, last week summoning retail bosses from the UK's 'big four'- Tesco, Sainsbury's, Asda and Morrisons - for a pep talk on their environmental policies.

Consumers are also exerting influence, with NGOs and pressure groups such as the 215,00-member Women's Institute lobbying for an end to excess packaging. A recent IGD report showed that more than half of British shoppers care about the green credentials of what they buy, and the impending introduction of variable charges for household refuse collection will ram this point home to many of the as yet unenlightened.

Inevitably, a mixture of motives is informing the current upsurge in green thinking among retailers, not all of them altruistic. Ian Bowles, head of CSR at Asda, spoke candidly to just-food: "We are working on landfill and other environmental issues because it's the right thing to do, but it's also a commercial no-brainer. Impending waste tax hikes to GBP35 (US$64.5) per tonne would bring Asda on-costs of GBP3m if we failed to act to reduce the amount we send to landfill. On top of this, the UK is fast running out of landfill sites, and there's a distinct lack of incineration capacity too."

Bowles added that the drive to reduce packaging would initially concentrate on fresh produce, as research has indicated that this is where consumer acceptance is highest and where the use of packaging as a marketing tool is less habitual. Nevertheless, it is not a simple matter of removing packaging; there are ramifications. "People ask us why we wrap a cucumber," he said, "and we have to explain that it enhances shelf life".

Herein lies the rub: Environmental best practice does not always go hand-in-hand with convenience or that other overriding consumer concern, price. Asda and other retailers will have to tread carefully to offer leadership on packaging without upsetting customers for whom convenience is paramount. While some shoppers actively seek out food with minimal packaging, there are many who still appreciate the ease and simplicity of the pork chop on the plastic tray, the shrink-wrapped sweetcorn and the single-portion yoghurt pot.

When all is said and done, retailers' motives for going green are a sideshow. The crucial factor is that they take responsibility both for their own environmental footprint and for helping shoppers to recycle, or better still reuse, or best of all reduce the amount of packaging they bring home in the first place.