By Aruna Viswanatha and Jessica Wohl

WASHINGTON/CHICAGO, Jan 10 (Reuters) - U.S. lawmakers increased public pressure on Wal-Mart Stores Inc on Thursday by releasing company emails they said contradicted prior statements about when senior executives knew of bribery allegations tied to its Mexican affiliate.

The emails show that senior Wal-Mart executives including current Chief Executive Mike Duke knew as far back as 2005 of allegations that company representatives had bribed officials in Mexico.

Wal-Mart quickly refuted the characterization of the emails saying they were consistent with the company's prior comments.

The bribery allegations surfaced in a New York Times report last year that described how the company had intentionally stifled an early internal probe into allegations that Wal-Mart de Mexico officials had paid bribes to help build stores there.

Elijah Cummings, the top Democrat on the U.S. House Oversight Committee, and Henry Waxman, the top Democrat on the House Energy and Commerce Committee, opened an inquiry into the matter in April. The U.S. Justice Department and the Securities and Exchange Commission are also separately investigating the matter.

The full emails, previously unreleased though mentioned in the Times' reporting, demonstrate the extent to which senior lawyers for the company briefed Duke and other top executives about the Mexican allegations in 2005.

One email from Wal-Mart General Counsel Thomas Mars in October 2005, for example, provided Duke with a memo summarizing the allegations with a note saying: "You'll want to read this. I'm available to discuss next steps."

The company handed off that internal inquiry back to its Mexican affiliate and essentially buried it then, according to the New York Times report.

Cummings and Waxman said the emails appear to be inconsistent with statements a Wal-Mart spokesman made in a second New York Times article in December of last year.

In that article, spokesman David Tovar said executives were aware of protesters who opposed the building of a Wal-Mart store in San Juan Teotihuacan, Mexico, in 2004 but did not know about the corruption allegations.

On Thursday, Wal-Mart spokeswoman Brooke Buchanan said there was no contradiction between Tovar's statement in the article referencing activity in 2004, and the emails from 2005.

She also said the company had already turned over the newly released documents to the DOJ and the SEC. "There is no new information in the letter released today," Buchanan said.

Cummings and Waxman, in their letter to Duke dated Thursday, also asked the company to make available to their committees Maritza Munich, who was general counsel of Wal-Mart International in 2005 and authored one of the newly released emails.

They said they had been requesting a meeting with Munich since last June, and asked Duke to respond by Jan. 24.

"We are exploring ways to make additional information available and are committed to doing whatever we can to appropriately address their requests," Wal-Mart's Buchanan said.

Wal-Mart shares fell 0.8 percent to $68 in afternoon trading.

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