Protesters of social organizations, public and private schools' students and residents take part in a demonstration protesting against the outcome of the July 1 general elections, in Mexico City, capital of Mexico, on July 22, 2012. Protesters marched to the Zocalo in downtown Mexico City. Thousands of demonstrators marched through Mexico City on Sunday to protest the outcome of the July 1 general elections, which declared Institutional Revolutionary Party (PRI) presidential candidate Enrique Pena Nieto the winner. (Xinhua/Rodrigo Oropeza)

Thousands of demonstrators marched through Mexico City on Sunday to protest the outcome of the July 1 general elections, which declared Institutional Revolutionary Party (PRI) presidential candidate Enrique Pena Nieto the winner.

Organized by Mexico's YoSoy132 student movement, the anti-Nieto rally began with protestors gathering outside Los Pinos, the official residence and office of Mexican president. The demonstrators then marched along the city's main avenue Paseo de la Reforma to the main square.

The demonstrators rejected what they called the "imposition" of Nieto as president, saying parties on both the right and left sides have accused the once-ruling PRI of winning the elections through voter buying and fraud.

According to the Federal Electoral Institute (IFE), which organized the elections and tallied the results, Nieto won with 38.21 percent of the little more than 50 million votes cast. Runner-up Andres Manuel Lopez Obrador, of the left-leaning Progressive Movement led by the Democratic Revolution Party (PRD), garnered 31.59 percent and Josefina Vazquez Mota, of the ruling conservative National Action Party (PAN), obtained 25.41 percent.

Organizers said some 10,000 people marched through the capital, while police put the figure at 5,000.

Joining the student protestors were members of Mexico's electricity workers union, the national teachers union, among other interest groups.

Some protestors carried banners and placards that read "No to the imposition," "IFE equals fraud" and "Death to Televisa." Opponents claimed the nation's main television broadcaster skewed coverage in favor of Nieto.

Protestors also carried messages criticizing the nation's electoral tribunal, which has until Sept. 6 to rule on the validity of the elections and Nieto's victory.

PAN and the PRD last week presented the electoral court with what they said were hundreds of boxes of evidence showing the PRI purchased votes with illicit money that may have been derived from drug trafficking.