By Elinor Comlay and Anahi Rama
MEXICO CITY (Reuters) - The front-running candidate for Mexico's presidency and lawmakers on Monday called on authorities to investigate allegations of bribery at the Mexican unit of Wal-Mart Stores Inc, though prosecutors said it may not be a federal matter.
Opposition lawmakers urged Mexico to launch a probe into the allegations, and Enrique Pena Nieto, the favorite to succeed conservative President Felipe Calderon, backed them up.
Mexico's attorney general would only look into the accusations against Wal-Mart de Mexico (Walmex) if asked to do so by the finance ministry or the economy ministry, a government official said on condition of anonymity.
Officials at the finance and economy ministries could not immediately be reached for comment.
Still, Attorney General Marisela Morales assured Mexicans on that her office would act promptly if given the case.
"If it becomes a matter for us, of course we will act and we will request whatever necessary," she told El Universal daily.
The New York Times reported over the weekend that retailer Wal-Mart had silenced an internal investigation into hundreds of suspect payments worth more than $24 million made to expand its business in Mexico.
A campaign spokesman for Pena Nieto, the candidate of the opposition Institutional Revolutionary Party (PRI), said he wanted the allegations to be investigated.
Andres Manuel Lopez Obrador, presidential candidate of the Party of the Democratic Revolution (PRD), said on Sunday that the allegations showed the government was "rotten," and he expressed dismay that the case was so far only being investigated outside Mexico.
Two opposition left-wing senators on the Senate's Banking and Public Credit Commission also demanded a probe.
"If licenses were given out where they shouldn't have been, there's fraud not only in the cities where that happened, but also there could have been fiscal fraud," Francisco Javier Castellon of PRD was quoted as saying in Monday's edition of daily Rumbo de Mexico.
Wal-Mart said on Saturday that it had begun an investigation last fall into its compliance with the U.S. Foreign Corrupt Practices Act. It said it disclosed the probe to the U.S. Department of Justice and U.S. the Securities and Exchange Commission.
"Unfortunately, we're aware that at this time there are questions we do not have answers for. We would like to be able to say more, but we are not prepared to risk the integrity of the investigation," said a further statement from Walmex on Monday, after its shares fell more than 11 percent.
While political pressure for action may increase in Mexico ahead of presidential elections on July 1, corruption-weary Mexicans barely raised eyebrows when they read of the bribery allegations in local newspapers.
Bribery and corruption is pervasive in Mexico, where the justice system is weak and lower-level public sector workers earn relatively meager salaries. One study last year by Transparency International showed that Mexican companies were perceived to be the third most likely behind those in China and Russia to pay bribes abroad.
Still, the country has been taking steps to turn around this image and an anti-corruption law was recently passed by Mexico's lower house that would give the country new powers to fine companies for corruption.
"It is important for Mexico to show it is tough on corruption," said lawyer Salvador Mejia, partner at Torres, Martinez y Mejia in Mexico City. "I can definitely see Walmex being investigated further here."
Walmex is due to report first-quarter financial results after the market closes on Monday.
(Additional reporting by Mica Rosenberg; Editing by Steve Orlofsky)