Costco Wholesale Corp.’s sales growth slowed in June, although food remained a bright spot as the struggling economy clouded the outlook for U.S. retailers

Dollar sales of fresh meat at Costco rose by “mid-single digits” on a percentage basis last month, compared with the same period in 2009, David Sherwood, the company’s director of investor relations, said in an e-mail today.

While pounds of meat sold fell by low single digits, it was still a “good month” for back ribs, spare ribs, organic beef and bagged frozen seafood, Sherwood said.

In fresh produce, sales rose by low single digits in dollar and volume terms, Sherwood said. It was a “good month” for blueberries, strawberries and oranges, he said.

Club stores such as Costco, along with general merchandisers like Target Corp., are a growing market for U.S. meat, produce and dairy producers because consumers have increasingly sought lower prices and access to nonfood items, such as fuel and apparel, at the same locations they buy groceries.

Costco’s comparable store sales have risen in eight of the last nine months. In a statement today, Costco said sales at U.S. stores open at least a year, excluding gasoline, rose 1 percent during the five weeks ended July 4 compared with the same period in 2009.

Also today, Target said June comparable sales rose 1.7 percent compared with the same period in 2009. Sales trends in categories including food and healthcare “remained strong” last month, Target chief executive office Gregg Steinhafel said in a statement.

Still, the overall picture for U.S. retailers has grown increasingly uncertain as high unemployment persists, analysts said.

A steady improvement in consumers’ spending intentions earlier in the year stalled in June, according to industry consultant Kantar Retail.

June sales results “are positive, but the recovery in retail sales will be challenged in the coming months as long as doubts grow among shoppers,” Frank Badillo, senior economist with Kantar, said in a statement today. “It’s clear that the news from the Gulf to Europe is starting to affect the outlook among shoppers.”

Costco’s 1-percent comparable-store sales growth last month slowed from a 5-percent increase in May. The most-recent five-week period covered 33 days, one fewer than the same period in 2009, Costco said.

Including gasoline, Costco’s net company-wide sales during the five-week period ended July 4 totaled $7.33 billion, up 6.7 percent from a year earlier.

Costco, which operates 524 stores in the U.S., Canada, Mexico and Puerto Rico, wouldn’t provide a dollar sales figure that excluded gasoline.

Also today, BJ’s Wholesale Club Inc., which has 189 stores in 15 states, said comparable store sales rose 3.2 percent excluding gasoline during the five weeks ended July 3.

Wal-Mart Stores Inc., the top U.S. club store operator, had 596 Sam’s Club stores at the end of 2009.