PREVIEW-Walmex Dec monthly sales seen weakest all year

By Cyntia Barrera Diaz and Gabriela Lopez

MEXICO CITY, Jan 6 (Reuters) - Mexico's top retailer Walmex is expected to post its weakest monthly sales of 2008 when it discloses December figures on Wednesday, as the economic slowdown squeezes consumption.

Mexican retailers came up with some of their most daring marketing campaigns ever for Christmas 2008, using blanket advertising as they struggled to maintain sales and counter high inflation, unemployment and consumer wariness.

Walmex offered lengthy credit facilities on plasma screens and washing machines -- even giving 18 months' interest-free credit on Christmas trees -- and pledged to reimburse sales tax at the checkout for large purchases over the holiday period.

But it was not enough to sway nervous consumers.

According to a poll of four sector analysts, Wal-Mart de Mexico's (WALMEXV.MX) same-store sales will show a fall of 1.4 percent in December from a year earlier.

The previous monthly sales decline was in September, down 0.7 percent, compared with Walmex's strongest 2008 result of 11.7 percent growth in March.

"We expect meager same-store sales results across the board, as a tough competitive environment, low average tickets, and negative calendar effects offset retailers' aggressive discounts," Credit Suisse wrote in a report. December 2008 had one Saturday and one Sunday less than in December 2007.

Same-store sales are those recorded at outlets that have been open for at least 12 months and used by analysts as a key performance gauge.