Best Buy and Circuit City, the nation’s two biggest consumer electronics sellers, on Friday reported strong December sales, a bright spot in a month that was weak for many other retailers.

Best Buy Co., the largest U.S. consumer electronics retailer, said sales for December rose 7 percent at stores open at least 14 months, better than it had expected. It credited “high double-digit” increases in high-end televisions, and employees who increased the number of customers who bought products during store visits.

Rival Circuit City Stores Inc. said sales grew 4.2 percent for the month at its stores open at least a year. Such measures, called same-store or comparable-store sales, are key retail indicators.

Best Buy said its overall December revenue grew 15 percent to $6.6 billion. Circuit City said total sales grew 5.9 percent to $2.1 billion.

On Thursday, Wal-Mart Stores Inc. and Target Corp. both reported strong electronics sales during December.