NEW YORK – Walmart Stores Inc. CEO Mike Duke found out in 2005 that the retailer’s Mexico unit was handing out bribes to local officials, according to emails obtained by lawmakers.

The emails contradict earlier claims by Walmart senior executives that they weren’t aware of the bribes.

Democratic congressmen Elijah E. Cummings and Henry A. Waxman, who are investigating bribery charges at Walmart’s Mexico division, on Thursday released emails that indicate Duke and other senior Walmart officials were informed multiple times starting in 2005 about the bribes. U.S. law forbids American companies from bribing foreign officials.

The lawmakers shared the emails, which they say they got from a confidential source, with Walmart on Wednesday, and sent a letter to Duke asking for a meeting to discuss them.

“It would be a serious matter if the CEO of one of our nation’s largest companies failed to address allegations of a bribery scheme,” according to the letter to Duke written by Waxman and Cummings.

Allegations first surfaced in April that Walmart failed to notify law enforcement that company officials authorized millions of dollars in bribes in Mexico to speed up getting building permits and gain other favors. Walmart has been working with government officials in the U.S. and Mexico on that investigation.

The company also has been conducting an internal investigation into the matter. And last November, the retailer said in a filing with the Securities and Exchange Commission that it was looking into potential U.S. bribery law violations in Brazil, China and India.

The Mexico bribery allegations were first reported by The New York Times. Last month, the paper published another story focusing on how Walmart’s Mexico division offered large payoffs to get things that the law prohibited.

The story focused on how Walmart paid $52,000 to secure approval to build its store in Teotihuacan on the site of ancient ruins. Although local zoning would have prohibited Walmart from building its store, the Times reported that the company allegedly bribed local officials to have that map redrawn.

The emails released Thursday include a November 2005 message from Maritza Munich, then general counsel of Walmart International, to Duke and other senior Walmart executives. The email informed them of charges related to bribes paid to obtain permits for a store in Mexico.

Another email referenced bribes paid to obtain permits for the Teotihuacan site.