The reports of Wal-Mart de Mexico bribing foreign officials just surfaced last spring, but two Congressmen say the company's CEO was personally informed in 2005.
The congressmen specifically cite an email from the retailer's then-general counsel, telling the executives about bribes paid to obtain permits for a store.
A Wal-Mart spokeswoman says this information has been part of the company's ongoing investigation for more than a year.
The U-S has a Foreign Corrupt Practices Act, which prohibits American companies from bribing foreign officials.
Wal-Mart said in November that it has spent millions to make sure it complies with the law.