Starbucks Corp. (SBUX), the world's largest coffee-shop chain, Wednesday said sales at stores open at least a year rose 8 percent in August, the first time growth fell below double-digits in nine months.

Ongoing demand for a new line of summer drinks, including an ice-blended "light" version of the company's popular "Frappuccino" (search) coffee drink, helped lift revenue to $418 million for the four weeks ended Aug. 22, up 25 percent from the same period a year earlier.

Starbucks, which is preparing to raise coffee prices beginning Oct. 4, has been posting double-digit gains in same-store sales since November of last year. But Chairman Howard Schultz said that growth was above expectations.

"We are very pleased with our strong monthly results during August, which again exceeded the Company's longer-term targets for both revenue and comparable store sales growth," Schultz said in a statement.

The number of Starbucks stores worldwide increased to 8,337 in August, a net gain of 90 stores. The total includes 5,945 U.S. coffee shops and 2,392 international units.

The same-store sales increase exceeded the Seattle company's projection for monthly increases of 3 percent to 7 percent. Starbucks has said sales were likely to top that range over the near term.

Starbucks launched a new version of its popular Frappuccino beverages this summer to tap into the growing popularity of reduced-calorie and reduced-fat menu choices for Americans.

New versions of its ice-blended drinks were also introduced in the United States, such as Strawberries and Creme, Java Chip and Vanilla Bean.