Every little helps. Or so a certain business goliath would have us believe. And a similar mission statement seems to have been adopted by green campaigners as they urge consumers to do their little bit and buy environmentally friendly goods... but with very little effect, claims one campaigner controversially.

"Green consumerism is an oxymoron," Greenpeace director John Sauven bluntly informed delegates from the world's biggest food and drink companies at a recent CIES marketing forum. "There's a thought process out there that says all we need to do is make slightly different shopping decisions to make a difference. But we waste too much and need to consume less."

To get them to do that, supermarkets have to raise their game, believes Sauven. "We must take responsibility as individual consumers, but most problems are way beyond the scope of purchasing decisions," he says. "We need a paradigm shift from big business and government."

Sauven's comments ruffled feathers at an event where environmental achievements were top of the agenda. While Tesco spoke at length about its initiatives, such as giving out 'green' Clubcard points to shoppers who bring their own bags, Sauven attempted to shift the thinking from the little man's weekly shop to the deep pockets of big business.

"If, as a company, you want to move operations to China then take your eco-factories that meet UK standards with you," he argues. "We can't just blame the Chinese for the environmental problems we face there. You can't outsource and then say it's someone else's problem. You must take responsibility. The longer supply chains become, the more possible problems we face."

Clearly the multiples were not going to like someone arguing that people should consume less and therefore buy less, and they have been quick to contest Sauven's views since the forum. Tesco, which launched an eco-friendly household range called Greener Living last year, described Sauven's argument as short-sighted. "We disagree completely," says a spokesman. "It is through individual actions that we can make a real difference. As individuals we cannot absolve ourselves of responsibility for our actions. Tesco has upwards of 17 million customers every week. Everyone can do their bit."

Asda adopts a similar line. "It is fair to say that one customer will not change the world," concedes Asda corporate policy manager Julian Walker-Palin. "But by listening to customers and finding ways to help them make positive choices, we have worked together to make real differences. We will continue to push the boundaries of sustainability to make green living affordable for all." In other words, it is not about how much people buy, but what they buy, he suggests.

The problem, points out Greenpeace campaign manager Andy Tait, is that there's only so far green manufacturers can go in making environmental products for the masses - which means the sector will always be the preserve of wealthier consumers. "Of course consumers should be making positive ethical purchasing decisions, such as buying responsibly sourced timber furniture from Asda or B&Q," says Tait.

"But on the other hand, the problem that truly progressive companies such as Ecover have is that costs go up when they source responsibly, making it harder to compete. As long as the ethical option in the supermarket remains niche, it is simply not enough."

And that means that in the short term the focus of organisations such as Greenpeace will be on encouraging consumers to buy less. In the long term, supermarkets will need to work with manufacturers to make 'going green' easier for all consumers, irrespective of the size of their wallets. One day, he says, 'green consumerism' may become less of an oxymoron.

"I want supermarkets to have already solved the green problem for me," he says. "I don't want to go into the shop and read all the labels. I want to see products on shelf that are the best they can be in all respects, with all ethical choices taken away from me."n