The company's statement came in response to a new report by The New York Times saying 19 store sites across Mexico were the target of Wal-Mart bribes.
Among those stores is one near Teotihuacan, the site of the famous pyramids outside Mexico City. The Times said Wal-Mart de Mexico paid more than $200,000 to circumvent zoning and other laws preserving archaeological sites to get the store built in 2004.
A Wal-Mart statement said the Teotihuacan store is part of the company's investigation that began about a year ago. The Times first reported on allegations of Wal-Mart bribery in Mexico last April.
Following the Times story late Monday, Wal-Mart's shares fell 1.5 per cent on the Mexican Stock Exchange to 42.49 pesos a share.
The company said that it opened an internal investigation at the end of 2011 and that it has taken some measures to stop corrupt practices.
"The opening of the Bodega Aurrera store in San Juan Teothihuacan, which took place in 2003-2004, and to which the New York Times refers to, is part of the investigation," it said.
Wal-Mart said that because its own investigation continues, it would not comment about specific accusations. But it said "it is willing to completely co-operate with authorities in any investigation about the permits and licenses it has been given."
The Times said it had identified 19 stores in Mexico that were opened through bribes and emphasized the case of the Bodega Aurrera store near the Teotihuacan pyramids and for which, according to the report, the chain paid $200,000 in bribes to local officials.
The Public Administration Department, Mexico's federal anti-corruption agency, said last April that it was investigating the permits issued to Wal-Mart Mexico but has not yet reported any findings. The agency said Tuesday that it wouldn't comment about the case until it finished its investigation.
The Attorney General's Office also opened an investigation and has not released its findings.
Federico Reyes Heroles, president of the board of directors of Mexican Transparency, a non-profit organization that studies corruption in Mexico, said authorities across the country should commit to stamping out corruption and preventing cases like that of Wal-Mart.
"If there were commitments like there are when it comes to certifying police officers as trustworthy, then they (officials) would have to answer to society. Otherwise, nothing happens," Reyes Heroles said.
Mexican President Enrique Pena has proposed creating an independent national anti-corruption commission to replace the Public Administration Department. The agency's head is currently appointed by the president, which for some critics does not guarantee impartial investigations.
The Times' article brought back memories to local residents who tried to stop construction of the Bodega Aurrera in Teotihuacan. The story said Wal-Mart paid local authorities a bribe of $52,000 to change a zoning map.
"It was all a fraud," said Emma Ortega, who was the leader of the Civic Front in the Defence of the Teotihuacan Valley.
Ortega said local authorities assured her at the time that they wouldn't issue construction permits to Wal-Mart, but months later the company began building the store and officials no longer would meet with the store's opponents.
Elio Castillo, director of urban development in the municipality of Teotihuacan and who was not in office at the time the permits were issued, said the documents contain no irregularities.
"For us they met all the prerequisites set by the law and have all the authorizations," Castillo said. He added that all building records are open to anyone who wants to review them.Suggest a correction