Wal-Mart Stores Inc is shaking up its e-commerce structure, putting the people who run stores in developed markets such as the United States in charge of the websites in those countries, according to an internal memo obtained by Reuters on Friday.

That decision and other e-commerce moves, which are being announced to employees on Friday, also include the departure of two e-commerce executives.

Raul Vazquez, who led the e-commerce developed markets group and Steve Nave, who was the leader of the Walmart.com business in the United States, decided to leave the company, Wal-Mart, the world's largest retailer, said in the memo.

Wal-Mart does not disclose the percentage of sales that come from its online business. The company's fiscal 2011 sales were $419 billion.

Building up online sales is an important growth strategy for the retailer, which has seen sales at discount stores open at least a year fall for two years.