Retail giant Wal-Mart Stores Inc has admitted it is investigating reports that it engaged in systematic bribery to clear the way for store openings in Mexico during the early 2000s.

The statement, released on Saturday (21 April), follows a report by the New York Times that discovered investigators appointed by Wal-Mart found a paper trail of "hundreds of suspect payments totalling more than $24m" used to bribe Mexican officials to speed up store openings.

The investigators also found documents showing that Wal-Mart de Mexico's top executives not only knew about the payments but had taken steps to conceal them from Wal-Mart's headquarters in Bentonville, Arkansas, the New York Times reported.

Executives were allegedly briefed about the payments after they were first discovered in 2005. Eduardo Castro-Wright, who was chief operating officer of Wal-Mart de Mexico until 2005, and is now vice chairman of the company, was described as the "driving force" behind the bribery in the report.

Former executive Sergio Cicero Zapata, who worked in the company's real estate department until 2004, told the New York Times he helped organise years of payoffs, and that following the arrival of Castro-Wright in 2002, the number of bribes soared.

The Times looked at thousands of government documents related to store permit requests throughout Mexico and found many examples of permits being granted within weeks or days of the company's payments to two outside lawyers who gave cash to officials.

Wal-Mart vice president of communications, David Tovar admitted that as the investigation is ongoing, the retailer doesn't yet "have a full explanation of what happened."

He added: "It would be inappropriate for us to comment further on the specific allegations until we have finished the investigation.

"We are working hard to understand what occurred in Bentonville more than six years ago and are committed to conducting a complete investigation before forming conclusions. We don't want to speculate or weave stories from incomplete inquiries and limited recollections, as others might do.

"Unfortunately, we realise that, at this point, there are some unanswered questions. We wish we could say more but we will not jeopardise the integrity of the investigation."

Tovar emphasised that the retailer takes compliance with the US 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".

"We will not tolerate non-compliance with FCPA anywhere or at any level of the company" emphasised Tovar.

Tovar said 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. We are deeply concerned by these allegations and are working aggressively to determine what happened," he said.

The company said it began the investigation in the autumn of last year and the investigation is being conducted by outside legal counsel and forensic accountants. It has met voluntarily with the US Department of Justice and the Securities and Exchange Commission to self-disclose the ongoing investigation of the matter.

"In a large global enterprise such as Walmart, sometimes issues arise despite our best efforts and intentions. When they do, we take them seriously and act as quickly as possible to understand what happened.

"We take action and work to implement changes so the issue doesn't happen again. That's what we're doing today," the retailer said.