Wal-Mart lawyers have identified India, China, South Africa, Brazil and Mexico as the most corrupt countries, according to a letter from two congressmen investigating the bribery charges leveled against the company.

The lawyers, retained to review Wal-Mart anti-corruption compliance globally, said these were the regions with the highest risk of corruption.

The letter from Democratic Representatives Elijah Cummings and Henry Waxman said Wal-Mart had revised its program to include measures to curb increasing corruption claims following the review.

In April, Wal-Mart was hit by allegations that it sought to cover up a bribery campaign orchestrated by its top executives in Mexico to facilitate rapid penetration into the region. It was reported that executives paid bribes to Mexican officials to acquire licenses for new stores and that even after obtaining evidence the internal investigation was closed without informing law enforcement officials.

Cummings and Waxman wrote to Wal-Mart CEO Michael Duke asking him to allow access to documents about the lawyers' review and recommendations and to those regarding the potential violations of the Foreign Corrupt Practices Act, which forbids the U.S. corporations from bribing foreign officials.

The congressmen said Wal-Mart hadn't allowed them to question any of its employees and that the company's actions significantly inhibit our ability to investigate the allegations.

Wal-Mart is currently facing at least a dozen derivative lawsuits, seeking to alter the way the company is run and to recover any financial damages that the company faces for violating laws.

There have been no reports of Wal-Mart's response to the letter, but it has maintained that it is committed to a full and independent investigation and that it would be inappropriate for us or others to come to conclusions before the investigation is complete, Reuters has reported.