Wal-Mart Stores Inc is making progress bringing items and shoppers back to its U.S. stores, and turning around U.S. sales remains its top priority, President and Chief Executive Mike Duke said on Tuesday.

The Walmart U.S. discount chain's food department has improved and its general merchandise areas are well on the way to having the right assortment, Duke said at a Barclays conference in New York that was also broadcast over the Internet.

Duke also said that there is a tremendous long-term opportunity in sub-Saharan Africa. Wal-Mart's plan to buy 51 percent of South Africa's Massmart Holdings Ltd has been hung up by delays. The government approval process should be completed over the next few weeks, allowing Wal-Mart to move ahead with the deal, Duke said.

Wal-Mart is bringing back thousands of items, advertising its low price guarantee and taking other steps to try to win back shoppers who balked at an earlier plan that cut goods from stores and emphasized promotional prices.

Duke again said that achieving an increase in U.S. same-store sales -- a key gauge of retail health that measures sales at stores open at least a year -- is his first priority.

Walmart U.S., the largest part of the world's biggest retailer, has reported seven consecutive quarterly declines. Duke declined to say when those same-store sales should turn around, but he did say that he is seeing traction.

Wal-Mart's biggest growth opportunity remains the United States, where it is opening more supercenters and other types of stores, followed by the potential to expand in China, he said.

(Reporting by Jessica Wohl)