* December total sales up 5.4 pct in Mexico
* December same-store sales up 3.1 percent in Central America
MEXICO CITY Jan 7 (Reuters) - Mexico's biggest retailer, Wal-Mart de Mexico, said on Monday that sales at its Mexican stores open for at least a year rose 1.6 percent in December from a year earlier.
The Mexican affiliate of Wal-Mart stores Inc said total sales, including those from newly opened stores, increased 5.4 percent in December from a year earlier.
Same-store sales in Central America rose 3.1 percent in December from a year earlier.
Wal-Mart de Mexico, known locally as Walmex, opened 285 new stores and restaurants in 2012 throughout Mexico and Central America, the company said.
Walmex is under investigation by U.S. and Mexican authorities over allegations that it bribed local officials to speed up store openings.
Mexico's anti-corruption body said late last year that it has found no irregularities in its probe of permits and documents given to the retailer to open stores, but two audits are still underway.
The company may still face sizable fines in the United States related to the allegations, after a report by the New York Times provided more details about the scope of the alleged misconduct.