The Justice Department has been conducting a criminal probe of Wal-Mart for allegations of systematic bribery in Mexico, according to three people familiar with the matter.

The investigation was launched in December after Wal-Mart met voluntarily with Justice Department officials, revealing it was looking into whether its Wal-Mart de Mexico unit had bribed foreign officials to gain business. Wal-Mart said this weekend that it has also met with the Securities and Exchange Commission. The allegations were brought to light by the New York Times on Saturday.

The U.S. Foreign Corrupt Practices Act bans companies from paying foreign officials to get more business. The law has recently been targeted by lobbyists — including an arm of the U.S. Chamber of Commerce with ties to Wal-Mart — who criticize it as too broad and bad for business.

The Times investigation found that Wal-Mart de Mexico paid more than $24 million in bribes to win construction permits. When a whistleblower alerted top Wal-Mart executives in 2005, they launched an investigation that found evidence of the bribery but then shut down the inquiry. The company failed to report any of the information to law enforcement at the time, the Times story said.

The revelations threaten to blemish the cleaned-up image Wal-Mart has carefully put together in recent years after facing criticism that it paid workers too little and put mom-and-pop stores out of business.

As officials in recent years have stepped up their enforcement of the U.S. Foreign Corrupt Practices Act, the Chamber has been pushing for the law to be scaled back.

The U.S. Chamber Institute for Legal Reform, an arm of the Chamber that has been a leader in criticizing the law, listed two Wal-Mart executives as board members in its 2010 tax form: Jeff Gearhart, Wal-Mart’s general counsel, and Thomas Hyde, a former Wal-Mart corporate secretary who stepped down in August 2010.

Hyde was among the company executives who received initial reports of the alleged bribery in 2005, according to the Times story.

“We take compliance with the U.S. Foreign Corrupt Practices Act (FCPA) very seriously and are committed to having a strong and effective global anti-corruption program in every country in which we operate,” David Tovar, Wal-Mart’s vice president of corporate communications, said in a statement Saturday. “Many of the alleged activities in The New York Times article are more than six years old. If these allegations are true, it is not a reflection of who we are or what we stand for.”

A spokesman for Justice Department declined to comment. The people who confirmed the department’s investigation spoke on the condition of anonymity because the probe is ongoing.

Wal-Mart’s shares slid nearly 5 percent Monday, and the company faced more questions about how much it knew about the corruption and why it did not tell authorities. Reps. Elijah E. Cummings (D-Md.) and Henry A. Waxman (D-Calif.) sent a letter to Wal-Mart chief executive Michael Duke requesting an in-person meeting about the bribery allegations.

Labor critics again raised alarms about the company’s practices.

“The reported cover-up by Walmart executives at the highest levels exposes a core truth: Walmart cannot be taken at its word,” Joe Hansen, international president of the United Food and Commercial Workers International Union, said in statement.

One in five Wal-Mart stores is in Mexico. Wal-Mart de Mexico is the company’s largest foreign subsidiary.

Staff writer Tom Hamburger contributed to this report.