ShopperTrak, which monitors the number of people walking into stores across the United States, said foot traffic fell 3.3 percent in the week ended Dec. 22 from last year.

However, sales increased 39.1 percent and traffic rose 32.0 percent compared to the previous week, as procrastinators rushed to finish last-minute shopping, ShopperTrak said.

Last week, ShopperTrak lowered its holiday season forecast, calling for sales in November and December to increase only 2.5 percent from 2011, down from 3.3 percent.

The Saturday before Christmas, Dec. 22, was the second-busiest retail sales and foot traffic day of the year, behind Black Friday on Nov. 23, the traditional start of the holiday shopping season, ShopperTrak said.

Shopping on the day after Christmas probably was not as strong this year as it was in 2011, ShopperTrak said. This year, Dec. 26 fell on a Wednesday, and many people likely were back at work. Last year, the day after Christmas came on a Monday.

In contrast, data released by IBM Benchmark showed online sales on Dec. 26 rose 40.4 percent over 2011 and that Apple Inc's iPad drove more retail shopping than any other device.

Traffic via iPad was at 10 percent versus 8.8 percent and 5.7 percent for Apple's iPhone and Google Inc's Android platform respectively, according to the findings by IBM Benchmark, which analyzes data from 500 retailers nationwide.