By Anahi Rama
MEXICO CITY (Reuters) - Mexican authorities turned up the heat on Wal-Mart Stores Inc's
A day after the federal comptroller's office said it would look into the bribery reports about Wal-Mart de Mexico (Walmex)
No complaint has yet been lodged against the company, the attorney general's office said in a statement.
The steps by Mexican authorities follow a New York Times report on Saturday that alleged that Walmex made suspect payments worth $24 million to expand rapidly in the country, where it is the biggest retailer.
The scandal has knocked billions of dollars off the value of Wal-Mart's stock.
Separately on Thursday, the mayor of Mexico City, Marcelo Ebrard, said that authorities in the capital would conduct a thorough investigation of the newspaper's allegations.
"We'll see what this investigation brings, what other information we can get - and if we establish any irregularity, we'll have to act," Ebrard told reporters in Mexico City.
"We're checking store by store, everything. There are all kinds of different permits, land use, construction authorization, there are licenses," he added.
Wal-Mart already faces a criminal probe by the U.S. Department of Justice over potential violations of the Foreign Corrupt Practices Act (FCPA), a U.S. law that forbids bribing foreign officials.
The Mexican comptroller's office said it had begun checking federal paperwork and permits that Wal-Mart de Mexico, known as Walmex, obtained to open and operate stores in Mexico.
Walmex's operations in the city proper include 23 Wal-Mart brand superstores, according to Walmex's website. It also owns dozens of other businesses in Mexico City including smaller supermarkets.
Separately, the Mexican environment ministry said it was asking the comptroller's office to investigate seven cases where Wal-Mart needed environmental clearance to build new stores to ensure there were no irregularities.
Mexican President Felipe Calderon said on Wednesday the scandal had made him "very indignant."
Around half of Mexico's 32 regional governments, which include the capital, told Reuters earlier this week they had no immediate plans to begin looking into the reports.
Walmex shares closed up 1.6 percent at 38.10 pesos ($2.89) and Wal-Mart shares closed up 2.8 percent at $58.95 on Thursday.
($1 = 13.17 Mexican pesos)
(Additional reporting by Miguel Gutierrez, Dave Graham and Mica Rosenberg in Mexico City and Jessica Wohl in Chicago; editing by Matthew Lewis)