UPDATE 1-Costco Aug same-store sales rise 9 pct

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Sept 3 (Reuters) - Costco Wholesale Corp (COST.O) reported a 9 percent rise in sales at stores open at least a year in August, as shoppers looked for better bargains on gasoline and food.

Same-store sales at its U.S. outlets increased 9 percent, while international division sales rose 6 percent.

Excluding gasoline price inflation, it said U.S. comparable sales would have been up 6 percent. On a local currency basis, international same-store sales increased 8 percent, said Costco, the No.1 U.S. warehouse club.

Many of Costco's clubs sell gasoline, luring shoppers looking to fill tanks with cheap fuel.

Costco's strongest domestic results were in the Midwest, Southeast, Texas and Northwest regions. California, where the company operates more than 110 of its 538 clubs, continued to lag, it said in a recorded call message.

Costco also said its food business continued to be strong with a high single digit comparable sales increase.

Net sales for the four weeks ended August 31 rose 12 percent to $5.41 billion.

"Tobacco sales which continue to trend downward did have a fairly negative impact of approximately minus 60 basis points" on reported comparable sales, the company said on the call.

The company plans to open eight or nine new warehouses before the end of the calendar year. (Reporting by Sweta Singh in Bangalore; editing by Rory Channing)