NEW YORK (CNN/Money) - Holiday sales rung up on Visa credit and debit cards continue to show strength, with a 16.1 percent gain in the week ended Dec. 12 compared with the same week in 2003, the spending card company said.

The No. 1 distributor of credit cards said spending totaled more than $26.7 billion in the week.

"Spending data for December continues to show that consumers are shopping in good numbers as the holidays approach, and we expect the busiest days are still to come," said Wayne Best, senior vice president of strategic and economic analysis for Visa, in a statement.

Overall sales volume for the three-day weekend from Dec. 10 to 12 was the strongest so far this holiday season, an increase of 15 percent over the "Black Friday" weekend of Nov. 26-28, Visa said.

The report said Dec. 10 and 11 rank first and second as the busiest shopping days of the 2004 holiday shopping season so far, with Visa recording sales worth $4.25 billion on the 10th and $4.16 billion on the 11th.

"While sales in specialty retail, gift, hobby and (department stores) have slowed in terms of percentage growth compared to the same period last year, the dollar volume increases week-to-week in 2004 remains impressive," Best added.

The National Retail Federation (NRF), the industry's largest trade group, expects total sales for the November-December shopping period to grow 4.5 percent to $219.9 billion, softer than last year's increase of 5.1 percent. The consensus among analysts is that total spending for the two months will grow about 4 percent.

The two-month period together can represent as much as 50 percent of sales and profit for merchants.

Visa says its cards account for 14 percent of the nation's personal consumption.