Wal-Mart stepped up its marketing campaign around locally-produced food this week, announcing a “locally grown” section of its web site, along with related signage inside stores designed to attract increasingly environmentally conscious consumers.

The retail giant said that it would source $400,000 in locally-produced food this year, including more local fruits and vegetables for its stores, but it was unclear how much of an increase in value this represented over last year. It already sources a fifth of its food locally - by which it means at a state level in the US - during the summer months, and partnerships with local farmers have grown by 50 per cent in the past two years.

The average distance traveled between producer and consumer is 1,500 miles, said the company, but it would not comment on how much it has or will reduce this distance.

However, critics said that while the initiative was to be welcomed there was a lack of clarity over the level environmental savings that are delivered by local sourcing initiatives.

“None of the supermarkets properly share what that means in terms of actual food miles,” said Kathy Dalmeny, policy director of Sustain, a UK advocacy group for better food and farming. “You continue to have cases of foods that are sold as local but can travel quite a long way before they get processed or labeled. The full meaning can be subject to more investigation.”

Erik Esse, director of the non-profit Local Fair Trade Network which advocates food producers’ rights in the upper midwest US, was cautiously hopeful about the announcement. “If it’s legitimate, than nothing could be better,” he said. “But when they got big into organics, they created pressure for lower prices, and that’s the opposite of what we want. We don’t want local farmers in the situation where they have even lower prices for their product because Wal-Mart is driving a hard bargain and buying from bigger suppliers.”

Wal-Mart failed to respond to questions about how its ongoing local produce initiative is changing logistics or supplier management strategies, how much it is saving overall from local food initiatives, or how the press release represented a change to its previous food procurement strategy.