The world's biggest retailer, Wal-Mart Stores, has launched an advertising account review for the first time in 30 years.

The US-headquartered company spent $578 million (€458.8m; £314.5m) on marketing last year through its incumbent agencies, the independent Bernstein-Rein Advertising in Kansas City and Omnicom Group-owned GSD&M, in Austin, Texas.

Both have said they will take part in the review, which is likely to set pulses racing among rivals over the coming weeks.

Gail Lavielle, senior director of corporate communications, said the review was in its early stages: "All we've done so far is just notify the [incumbents]." She added that its intent was to "make sure all of our messages are consistent across all media we use."

Wal-Mart is determined to broaden its appeal to upscale shoppers and persuade them to buy more than detergent in its stores. It is also pushing into urban markets ands wants to attract more sophisticated city types.

Its advertising account has been under scrutiny since chief marketing officer John Fleming joined from rival Target last year.

Data sourced from Adweek (USA); additional content by WARC staff