Marks & Spencer has claimed it has become the first major retailer to go completely carbon neutral, five years after launching its sustainability project Plan A.

All M&S-operated stores, offices, warehouses and delivery fleets in the UK and Ireland had been certified as carbon neutral, and it now recycled all its waste, and sent nothing to landfill, the retailer announced.

But it reported a decline in organic food sales since 2007 owing to reduced customer demand and a failure to convert a planned 20 million clothing garments to Fairtrade cotton because of supply chain difficulties.

It had also been unable to convert all fresh turkey, geese, pork and duck to free range while responding to customer demand to stock higher-welfare products.

The details were revealed in the retailer’s 2012 How We Do Business Report, published yesterday.