August sales at Wal-Mart Stores open at least a year rose a surprising 3 percent, the retail giant said on Thursday. Strongest sales for the leading discounter were in grocery and household items such as medicines.

Grocery sales were led by food and consumables, including value-priced meal solutions, Wal-Mart reported. Electronics, fitness equipment, and camping items also sold well.

"The underlying business performance for Wal-Mart U.S. continued to show strength and the improved relative performance has resulted in market share gains," said Eduardo Castro-Wright, Wal-Mart's U.S. president.

Most stock analysts were expecting same-store sales to increase only 1.6 percent, while Wal-Mart forecasted its own rise in sales of 1 to 2 percent excluding fuel sales. The Bentonville, Ark.-based retailer projected August sales would slow down, after the boost from tax rebates was over.

Wal-Mart said it expects its U.S. same-store sales for September, excluding fuel, to rise between 2 percent and 3 percent. The company said total net sales for the month of August rose 8.7 percent to $30.67 billion.

As of yesterday, fewer than 50 Wal-mart stores in the Gulf Coast area remained closed due to power outages and other issues related to Hurricane Gustav.