UPDATE 2-Mexico's Walmex posts 11 pct rise in third-quarter profit

* Walmex third quarter profit 5.256 billion pesos

* Quarterly revenue rose 11 percent on promotions

MEXICO CITY Oct 17 (Reuters) - Wal-Mart de Mexico, the country's biggest retailer, posted an 11 percent rise in third-quarter net profit on Wednesday that was driven by strong sales growth after the company launched aggressive promotions to lure consumers.

The company reported a profit of 5.256 billion pesos ($409 million) for the July-September period, in line with expectations in a Reuters poll. That compared with a profit of 4.731 billion pesos in the same quarter a year earlier.

A campaign offering interest-free payments on big ticket items such as computers and electronics fueled a jump in September sales after competition from other retailers pressured sales in the first part of the quarter.

The company, a unit of U.S. retail giant Wal-Mart Stores Inc , said third-quarter revenue rose 11 percent to 110.8 billion pesos, just above estimates.

Earnings before interest, tax, depreciation and amortization (EBITDA) rose nearly 15 percent in the period to 9.4 billion pesos, beating expectations.

Walmex Chief Financial Officer Rafael Matute said in a conference call that the company trimmed its guidance for the expansion in new floor space this year to a 7.7 percent increase due to slower-than-expected growth in Central America.

The company previously projected 8.1 percent growth in installed capacity.

Walmex shares have slumped more than 12 percent from a record high in April due to news of a U.S. Justice Department investigation of allegations that the company bribed local officials so that it could open stores more rapidly in Mexico. Mexican officials have opened their own probe.

As a result of the bribery probe, Walmex in June slashed its planned store openings for 2012 and cut investment spending by 11 percent.

Walmex opened 139 new stores in Mexico during the first nine months of 2012, down 35 percent from the number of stores it opened during the first nine months of last year.

Walmex Chief Executive Scot Rank said the company was still carrying out its own investigation into possible corrupt practices, but he did not provide any new details on the internal probe.

Walmex shares closed nearly flat at 38.99 pesos before earnings were released.