UPDATE 1-Costco August same-store sales up 7 percent

* August net sales up 9 percent at $5.9 billion

* Says gasoline prices, foreign currency gains helped

Sept 2 (Reuters) - Costco Wholesale Corp (COST.O), the largest U.S. warehouse club operator, reported a 7 percent rise in August sales at stores open at least a year, aided by a surge in gasoline prices and foreign currency gains.

Midwest, Texas, northwest and Los Angeles performed best for the company within the United States.

Internationally, Korea, Canada and Japan were the outperformers, Costco said on Thursday.

Analysts were expecting same-store sales to rise 4.2 percent, according to Thomson Reuters data.

Costco, which operates 572 warehouses across the world, said it gained from the strengthening of the Canadian dollar CAD=D4 as well as the Korean won KRW=.

For the four weeks ended Aug 29, net sales at the Issaquah, Washington-based company rose 9 percent to $5.9 billion.

Discounts and back-to-school selling had helped teen retailers Hot Topic Inc (HOTT.O) and Zumiez Inc (ZUMZ.O) beat August same-store sales estimates. [ID:nSGE6800LA] (Reporting by Krishna N. Das in Bangalore; Editing by Dan Lalor)