ISSAQUAH, Washington ( TheStreet) -- Costco ( COST), the warehouse retailer, said comparable-store sales in August rose 7% while net sales gained 9% to $5.9 billion. Analysts surveyed by Thomson Reuters expected Costco to report a same-store sales increase of 4.2%. Costco, in a statement Thursday, said U.S. same-store sales in August increased 6% and international sales jumped 11%. Excluding gasoline and foreign exchange, August same-store sales rose 5%; analysts had forecast a rise of 3.6% on this basis. Costco said fourth-quarter net sales rose 8% to $23.6 billion while same-store sales rose 6%. Fiscal-year net sales gained 9% to $76.3 billion and same-store sales were 7% higher. -- Written by Joseph Woelfel >To contact the writer of this article, click here: Joseph Woelfel >To submit a news tip, send an email to: email@example.com.