NEW YORK, July 15 (Reuters) - Wal-Mart Stores Inc (WMT.N), the world's biggest retailer, is preparing to hold a meeting on Thursday 16 July to announce the development of an index that will be used to measure the environmental impact of the products it sells in its stores.

Photo: Wal-Mart

"This summit represents a key inflection point in the process of designing and launching Wal-Mart's Sustainability Index, which is the tool Wal-Mart buyers will use to evaluate their 60,000 suppliers and determine the hundreds of thousands of products that end up on store shelves," the company states on a website designed for the event.

Wal-Mart said in a press release on Tuesday 14 July that it would hold a meeting on Thursday 16 July to discuss its plans "to address consumers' increasing expectations for more sustainable products and how measuring sustainability can drive innovation in the supply chain and in products consumers purchase."

Wal-Mart spokesman David Tovar said the retailer was not providing any comment on the event.

(Reporting by Nicole Maestri; Editing by Tim Dobbyn)