Three leading international press organizations called on Mexico's presidential candidates Tuesday to end the violence against journalists and the impunity of criminals.

The International Press Institute, or IPI, the World Association of Newspapers and News Publishers, or WAN-IFRA, and the World Editors Forum made their request in a letter addressed to the three leading presidential candidates.

"We are seriously concerned at the horrific levels of violence facing journalists in Mexico," the groups said in the letters, whose text was included in a statement posted on the IPI Web site.

"At least 53 have been murdered in the past 6 years and many more have disappeared. In very few cases have the perpetrators been brought to justice and those who kill and threaten journalists are routinely protected by a climate of impunity," the groups said.

The three press organizations called on Josefina Vazquez Mota, of the National Action Party, or PAN, Enrique Peña Nieto, of the Institutional Revolutionary Party, or PRI, and Andres Manuel Lopez Obrador, of the Party of the Democratic Revolution, or PRD, "to explain how they would end this intolerable situation and restore Mexico's democratic reputation."

The groups, moreover, called for an to impunity in the recent killings of journalists in "the most dangerous country for journalists in the Western Hemisphere."

The war launched by the government on Mexico's drug cartels has led to "self-censorship and massive news blackout have become common in some regions," the press groups said.

A regional human rights body, for its part, urged the government to take action in the wake of the killing of a journalist in Mexico last week.

The Office of the Special Rapporteur for Freedom of Expression of the Inter-American Commission on Human Rights, or IACHR, condemned the killing of journalist Victor Baez last Thursday in the eastern Mexican state of Veracruz.

"The federal and local authorities in Mexico are encouraged to take urgent measures to halt the wave of violence against journalists and to put into practice all of the available legal instruments to identify and sanction the perpetrators and masterminds of the latest crime," the Office of the Special Rapporteur said.

Nearly 80 journalists have been murdered in Mexico since 2000.

"The Office of the Special Rapporteur expresses its deep concern at the recurrence of extremely serious attacks against the press in Mexico, where at least seven media workers have been killed this year. Six of these deaths occurred in the state of Veracruz in circumstances that may be related to the victims' journalistic work," the rights body said.

Mexico will hold its presidential election on July 1, selecting a successor to President Felipe Calderon.

Nearly 80 million Mexicans will be eligible to vote for a new president, 628 legislators and thousands of other officials in the general elections. EFE