The world's largest retailer Wal-Mart has launched a series of television commercials designed to combat criticism about its employment practices.

Two adverts will run nationwide, one emphasising the legacy of founder Sam Walton, the other highlighting the health insurance plans it contributes to for more than 1.3m US employees.

Announcing the campaign, Wal-Mart said that a survey of employees conducted last summer found 88% believe the company is a good corporate citizen and 81% would recommend a job at Wal-Mart to a friend.