The left-wing candidate in Mexico's July 1 presidential elections, Andres Manuel Lopez Obrador, came in 3.3 million votes behind winner Enrique Pena Nieto from the centrist Institutional Revolutionary Party (PRI), a result Obrador has now said he will challenge in court.

Obrador, a former mayor of Mexico City, said that rival Nieto bought around five million votes with the help of local governors. There are allegations that the PRI used gift cards and food vouchers to win over voters.

"The massive vote buying operation was carried out before and on the day of the election," he told a news conference on Thursday. "In a free election the majority of those citizens would not have voted for Enrique Pena Nieto," he added.

'Baseless' accusations

PRI leader Pedro Joaquin Coldwell slammed Obrador's challenge, saying the leftist leader "throws out baseless accusations, offending millions of Mexicans."

Obrador also claimed that his rival, who garnered 38 percent of the vote in the recent elections, spent too much on his campaign.

He and his team turned in the petition along with at least 20 boxes containing alleged proof.

The court has until early September to deal with the challenge.

Meanwhile, Obrador has promised that next week he will reveal what he called "a national plan in defense of democracy and Mexico's dignity," without giving any details.

Nieto will bring the PRI back to power after 12 years in the opposition. It ruled Mexico for seven decades straight, often with authoritarian tactics to stifle political rivals and rig elections.

ng/slk (AP, Reuters)