NEW YORK (CNN/Money) - Wal-Mart Stores said it now expects December sales to be at the high-end of its previous forecast, boosted by better-than-expected sales in the weekend after Christmas.

The world's largest retailer said it sees sales at stores open at least a year -- a key retail measure known as same-store sales -- to come in 3 percent higher. Wal-Mart (Research) last week had guided sales for the month to be at the mid-point of a 1 to 3 percent range.

In a pre-recorded sales call, Bentonville, Ark.-based Wal-Mart said food and general merchandise sales last week were above plan while gift cards redemption for the week was "up significantly over last year."

Wal-Mart is expected to report final December same-store sales Thursday.

"The message may be that the finish to the holiday season was very good. However, Wal-Mart's monthly sales growth seen together is still on the weak side," said Michael Niemira, chief economist with the International Council of Shopping Centers (ICSC).

At the same time, Niemira said Wal-Mart's upgraded forecast is better news not only for itself but also for the retail industry because it supports the theory that retailers did indeed get that late-season push.

Niemira expects December sales to have risen between 3 to 3.5 percent. For the November-December holiday shopping period, he forecasts overall sales to come in between 2.5 to 3 percent.

The National Retail Federation (NRF), the industry's largest trade group, projects holiday sales to have grown 4.5 percent.

"If Wal-Mart's December comparable sales do go up 3 percent, that means they did much better in the last two weeks of the month," said Richard Hastings, retail economist with Variant Research.

"Sales at the Wal-Mart supercenters and at Sam's Club probably trended higher after the retailer corrected its promotional tactics after missing out on the early holiday sales momentum," said Hastings.

Shares of Wal-Mart dipped 24 cents to $52.82 on Friday.