The Bank of Mexico has been dragged into the dispute over the July 1 presidential election and is denying allegations from the left that it altered documents to cover up illegal money transfers.

"As administrator of the Interbank Electronic Payments System (SPEI), we provide the infrastructure and communications links for said system," the Bank of Mexico said in a statement.

"The transactions executed by the system are made exclusively by the financial institutions that maintain a direct relationship with public users," the central bank said.

"The fact is derived from this that the central bank does not have any responsibility with regard to the information on the receipts, given that the truthfulness and thoroughness of the information can only be confirmed by the bank receiving the funds," the Bank of Mexico said.

"Any modifications of the receipts can only be done via the direct instructions of the receiving bank," the Bank of Mexico said.

"As a result, the presumptions made recently raising questions about the actions of the Bank of Mexico and its officials are completely unfounded and lack truth," the central bank said.

Leftist presidential candidate Andres Manuel Lopez Obrador, who is challenging the election results, alleged last Friday that the Bank of Mexico altered a receipt for an electronic funds transfer totaling 50 million pesos ($3.8 million).

The forms were changed to hide the fact that the money had ended up in the hands of Luis Videgaray, who worked as campaign manager for Institutional Revolutionary Party, or PRI, candidate Enrique Peña Nieto, Lopez Obrador said.

Peña Nieto won the presidential election with 38.21 percent of the vote, while Lopez Obrador took second place with 31.59 percent, according to the final official results released by the Federal Electoral Institute, or IFE.

Lopez Obrador challenged the election results, alleging that the PRI and its allies exceeded campaign spending limits and engaged in vote-buying with funds obtained from illicit sources.

Lopez Obrador lost the 2006 presidential election to Felipe Calderon, of the National Action Party, or PAN, by 0.56 percent and has never recognized the results, claiming victory in the contest and declaring himself "president-elect."

Ricardo Monreal, who served as Lopez Obrador's campaign manager, said over the weekend that he planned to file a complaint against Bank of Mexico Gov. Agustin Carstens with federal prosecutors.

The TEPJF electoral court is expected to issue a ruling in the next few days on the challenge filed by Lopez Obrador's Progressive Movement coalition, either certifying Peña Nieto the winner or calling for a new vote.

The electoral court is expected to make its ruling by Sept. 6. EFE