Of 143,000 ballot boxes used during Sunday's vote for a new Mexican president, 78,012 are being opened and the votes recounted. Edmundo Jacobo, executive secretary of Mexico's Federal Electoral Institute said that the recount should be finished on Thursday.

There will also be a recount in 61 percent of the ballot boxes in the vote for the Senate and 60 percent in the vote for the lower house of Congress, Jacobo said. The final congressional counts were due on Sunday.

Defeated, second placed Andres Manuel Lopez Obrador of the Democratic Revolution Party has refused to accept the preliminary vote tallies which placed him behind Enrique Pena Nieto's Institutional Revolutionary party (PRI).

Lopez Obrador said the election campaign was marred by overspending, vote-buying and favorable treatment for Pena Nieto by Mexico's media. Lopez Obrador's supporters have claimed that ballot boxes were stolen and burned.

Videos posted on the internet have shown voters claiming they received credit with a major supermarket chain in exchange for their votes.

Pena Nieto has said they were faked and has denied wrongdoing.

In 2006, Lopez Obrador demanded a recount after losing to President Felipe Calderon by slightly more than half a percentage point, or some 250,000 votes. This time he finished more than 3 million votes behind Pena Nieto.

jm/mr (Reuters, AP)