Britain's Marks & Spencer is to step up its plans to go "green" by opting for more sustainable ingredients and agreeing a living wage for suppliers in its bid to become the world's most sustainable retailer by 2015.

M&S said in a statement on Monday its new plan would extend its original green targets that were introduced in 2007 and would make the company more efficient, develop new markets and build customer loyalty.

"It's therefore not just the right thing to do morally but also makes strong commercial sense," Chairman Stuart Rose said.

"Since we launched our eco plan, Plan A, in 2007 we've reduced our environmental impact, developed new sustainable products and services, helped improve the lives of people in our local communities and saved around 50 million pounds by being more efficient."

"Our extended Plan A will reach further and move us faster - covering every part of our business and reaching out to forests, farms, factories, lorries, warehouses and into our customers' and employees' homes."

M&S said its new commitments would include making sure all 2.7 billion food, clothing and home items carried at least one sustainable or ethical quality such as being fairtrade or free range.

It will also seek to determine and agree a fair, living wage for workers in such markets as Bangladesh, Sri Lanka and India, and provide training and education programmes.