Mexican President Felipe Calderon on Monday said vote-buying in the presidential election was "unacceptable" and urged election officials to investigate and punish the practice.

"The sale of political will, whether one or ten or a hundred, or thousand, is simply unacceptable," Calderon said in an interview with Radio Formula, adding that vote-buying is "a defect in our democratic quality that must be corrected immediately."

While expressing hope the election authority would "immediately rectify and punish" vote-buying, Calderon also doubted whether the allegations of irregularities would be sufficient to disqualify the election.

The Federal Electoral Institute (FEI) on Friday published final data based on scrutiny of the presidential elections, giving victory to Enrique Pena Nieto, candidate for the Institutional Revolutionary Party (PRI), who won 38.21 percent of the vote, as against 31.59 percent for his closest rival, Andres Manuel Lopez Obrador of the center-left Progressive Movement.

Obrador has denounced the alleged purchase of about 5 million votes for the PRI through strategies such as handing out prepaid gift cards from a grocery to voters in some districts, or exempting voters from taxes in the states run by the PRI.

The conservative National Action party (PAN) also condemned the PRI a week before the July 1 election for spending 700 million pesos (49.09 million dollars) in its campaign, an amount far exceeding the campaign spending cap of 300 million pesos (21.7 million dollars) set by law.

In the election, the PRI's Nieto finished first, followed by Obrador of the Progressive Movement and Josefina Vazquez Mota of the PAN, according to the FEI.

The FEI delayed the announcement of the election results because of the vote-buying allegations. The final results will be announced before Sept.9 and the new president is expected to take office on Dec.1.