NEW YORK (AP) — Wal-Mart Stores Inc. is expanding a test of a new checkout program that allows shoppers to scan items with their smartphones and then pay at self-checkout terminals.

The world's largest retailer launched what it calls its "Scan & Go" program late last year in about 70 stores in the Bentonville, Ark., area, where the retailer is based, as well as Atlanta. It is now testing the program in more than 200 stores. The new markets include Dallas, Houston, Austin, Texas; Denver, Portland, Ore., and Seattle.

It works like this: customers scan bar codes of the different products using the retailer's Scan & Go app on Apple Inc.'s iPads, iPhones or iPod Touch devices. The app generates a code, which can be scanned at the self-checkout terminals.