MEXICO CITY (Reuters) - Mexico's biggest retailer, Wal-Mart de Mexico , said on Tuesday that sales at Mexican stores open at least a year fell 1.9 percent in February.

The Mexican affiliate of Wal-Mart Stores Inc said February same-store sales in Central America also fell 1.9 percent from a year earlier.

Walmex said total sales, including those from newly opened stores, rose 2.1 percent in February from a year earlier.

The company opened eight new stores and restaurants in Mexico and Central America in February.

Walmex last month told investors that it expects to spend up to $1.4 billion on investments this year to increase store space by about 8 percent to 9 percent in Mexico, but it would not disclose how many stores it planned to open in 2013.

The retailer is under investigation by U.S. and Mexican authorities over allegations that it bribed local officials to speed up store openings.

Walmex said earlier on Tuesday it will hire an external attorney to take on a new role heading its legal, ethical and corporate affairs.

(Reporting by Elinor Comlay; Editing by Leslie Gevirtz)