Starbucks Corp. (SBUX) Wednesday said sales at stores open at least a year rose 10 percent in June, the eighth straight month of double-digit gains for the world's largest coffee-shop chain.

Revenue rose to $517 million for the five weeks ended June 27, up 26 percent from a year earlier.

The number of Starbucks cafes worldwide increased to 8,119 in June, a net gain of 134 stores. The total includes 5,784 U.S. coffee shops and 2,335 international units.

The same-store sales increase was slightly above Wall Street forecasts, but many analysts had predicted an out-sized gain, noting the company has routinely exceeded its own projections for monthly increases of 3 percent to 7 percent.

Several initiatives to speed customers through long store lines, including automated espresso machines, have boosted same-store sales by between 2 and 3 percentage points per month, according to analysts.

A stored-value purchase card has also helped Starbucks sell drinks faster, including a summer line-up featuring chocolate, strawberry and vanilla-flavored iced beverages.

Before the announcement, Starbucks shares closed at $43.49 in Nasdaq (search) trading, a gain of 28 cents, or 0.65 percent.