Protesters are accusing Enrique Pena Nieto, Mexico's newly elected president, of giving gifts to voters before the election.
Tens of thousands of people marched in Mexico's capital on Saturday to protest Enrique Pena Nieto's apparent win in the country's presidential election, accusing his long ruling party of buying votes.
The protesters were angered by allegations that Pena Nieto's Institutional Revolutionary Party gave out bags of groceries, pre-paid gift cards and other goods to voters ahead of July 1 national elections.
The students, unionists and leftists in the march carried signs reading, "Pena, how much did it cost to become president?" and "Mexico, you pawned your future for 500 pesos." Mexico City officials put the size of the crowd that reached its central Zocalo plaza at 50,000.
"The fraud was carried out before (the election), buying votes, tricking the people," said Gabriel Petatan Garcia, a geography student who carried a sign in Finnish.
Protesters also carried signs in English, Japanese, French, German and other languages to call the attention of the international press.
Pena Nieto, a youthful, 45-year-old married to a soap opera star, won last Sunday's election by 6.6 percentage points, according to the official count, bringing the PRI back to power after 12 years in opposition. The party had ruled Mexico for 71 consecutive years, with what critics say was the help of corruption, patronage and vote fraud.
PRI officials deny the vote-buying charge and say the vote was free and fair.
The final vote count had Pena Nieto getting 38.21 percent support, leftist Andres Manuel Lopez Obrador of the Democratic Revolution Party with 31.59 percent, and Josefina Vazquez Mota of the conservative National Action Party with 25.41. The small New Alliance Party got 2.29 percent.
The final vote count must be certified in September by the Federal Electoral Tribunal. The tribunal has declined to overturn previously contested elections, including a 2006 presidential vote that was far closer than last Sunday's.