The accounts allegedly used to buy votes for Institutional Revolutionary Party, or PRI, presidential candidate Enrique Peña Nieto will not be frozen, but the investigation of possible election law violations remains open, Mexico's Federal Electoral Institute, or IFE, said.

The governing National Action Party, or PAN, alleged on Tuesday that the PRI was giving its political operatives debit cards issued by finanical company Monex for an account containing 700 million pesos ($50 million) for buying votes.

The two debit cards presented as evidence "are part of a series of 9,924 cards that a legal person of a mercantile character contracted for with Monex for the April to October 2012 period," the IFE said.

"The total funding of the 9,924 cards reaches 70,815,534 pesos," the IFE said in a statement.

The legal entity will be asked to provide the names of each of the recipients of the debit cards, the IFE said, adding that a request had been filed with the federal tax administration for information about the entity and the individuals associated with it.

The complaints commission did not find any evidence that the funds deposited with Monex were to be used to buy votes, preventing the imposition of the measures requested by the PAN, the IFE said.

Roberto Gil, campaign coordinator for PAN presidential candidate Josefina Vazquez Mota, has unearthed new evidence of a clandestine financial network funded by the PRI to circumvent IFE rules, the PAN said.

Gil "read the testimony of a PRI operative in Guanajuato, who said he received a Monex card with 7,500 pesos and a promise that he would get another 10,000 (pesos) after" next Sunday's elections, the PAN said in a statement.

"It is obvious that the PRI is not naive enough to put 700 million pesos into an account in its own name. What is clear is that this operation, illegal in all its aspects, constitutes organized electoral fraud by the PRI," the PAN said.

Mexico will hold its presidential election next Sunday, selecting a successor to President Felipe Calderon.

Nearly 80 million Mexicans will be eligible to vote for a new president, 628 legislators and thousands of other officials in the general elections. EFE