Marks & Spencer has today reported impressive growth in sales and profits for the first half of its financial year as part of a performance that is likely to be interpreted as an early vindication of its high-profile climate change strategy.

Sales for the six months to the end of September were up 6.5 per cent on the same period last year to £4.2bn, despite "a tough market impacted by unseasonable trading conditions" throughout the damp summer.

The company also reported that its green product lines had enjoyed a particularly strong performance over the last year with Fairtrade food and drink sales up 22 per cent year-on-year to £56m and organic food sales up 43 per cent to £81m.

A spokeswoman for the company said it was too early to draw a clear correlation between the company's strong sales performance and its Plan A strategy to limit the company’s carbon footprint and develop more sustainable products, but she added that the early signs were that the initiative was enjoying some commercial success.

"The sales growth in our eco-product categories is pertinent and these are key areas that we are investing in expanding," she said. "We can’t at this time draw a direct link with sales performance, but Plan A is a long-term strategy and [M&S chief executive] Stuart Rose has been clear he believes a sustainable business can be highly profitable."

The announcement comes as M&S also revealed it has started using food waste to power some of its stores as part of a new biomass initiative that will see it run six of its stores from carbon neutral biomass power stations by early next year.

The company said it had already begun sourcing energy from an anaerobic digester in Shropshire that generates renewable energy from household waste, and would also begin start a similar biomass power station fuelled by cow slurry and agricultural crops from next spring.

Rose said the move made M&S the first major retailer to use food waste to power some of its stores, adding that the project was indicative of the changes being undertaken under the Plan A strategy.

He added that the retailer would also extend its carrier bag charging trial to 33 stores in the South West as it looks to reduce the number of plastic bags customers use.

The company has been charging customers 5p per plastic bag at stores in Northern Ireland for the past 16 weeks and has seen a 66 per cent reduction in the number of carrier bags used while also raising £40,000 for a local environmental charity.

"Our initial trial in Northern Ireland has shown us that introducing charging does make customers think twice about the number of bags they use, which is why we are extending [it] to the South West of England," Rose said. "If we see similar results and get an encouraging response from our customers in the South West, we plan to roll this out across the UK."