Yet the matter has gone completely unnoticed by the vast majority of the population, since none of the country's major mainstream media have reported on the situation.

In the meantime, the government continues to repeat that the right to free expression is fully guaranteed to journalists in Mexico, and numerous international organisations claim that there is a relative climate of freedom for the exercise of their profession.

But Mexican journalists themselves disagree. ”The situation of press freedom is worse under Fox,” Teodoro Rentería, president of the Federation of Mexican Journalists' Associations (FAPERMEX), which represents 9,000 of the country's 25,000 journalists, told IPS.

”It's true that journalists can speak out more and denounce things more than before, but it doesn't really count for much if the government doesn't pay any attention, and journalists are threatened for doing it,” he added.

In the three years and 10 months that Fox has been in power, there have been 10 documented murders of journalists, as compared to 19 during the six-year term of Ernesto Zedillo (1994-2000) and 57 under Carlos Salinas (1988-1994), both members of the PRI.

The majority of these killings remain unsolved and unpunished, although numerous investigations have directly implicated former government officials, police officers and drug traffickers.

Between January 2002 and July 2004, the Mexican National Human Rights Commission, an independent government agency, received 48 complaints of threats against journalists.

On Oct. 11, in an unprecedented act of protest, scores of Mexican journalists took to the streets in 10 of Mexico's 32 states to demand ”guarantees for full freedom of expression and exemplary punishment for the crimes and attacks against journalists.” A public declaration was signed by 232 of them.

The government's response to the protest -- sparked by the murders of four journalists in less than a year -- was to propose the creation of a working group to study their demands.

Eréndira Cruz, director of the non-governmental National Centre on Social Communication (CENCOS), told IPS that the media enjoys greater freedom today than during the years when the PRI was in power, but at the same time, ”objectively speaking, a state of alarm and of warning” has been created by the impunity surrounding those who threaten and kill journalists.

CENCOS joined with other similar organisations and independent journalists to organise the protest held on Oct. 11, which ironically was either totally ignored or given minimal coverage by most of the mass media in Mexico.

A writer with a major Mexican newspaper, who preferred to remain anonymous, ”so they don't label me as anti-union,” told IPS, ”I'm a moderately well-informed journalist, and I didn't see anything about the protest.”

He added, however, that in his view, the events that led to the demonstration ”are somewhat isolated occurrences. Given all of the pressures and dangers facing this profession, I would say that there is in fact freedom of the press in Mexico, because we have won it, and it isn't in any danger.”

But according to Leonarda Reyes, director of the Centre for Journalism and Public Ethics (CEPET), the freedom of the press that exists in Mexico is promoted by the federal government, while there are individual states ”where it doesn't exist, and that is what worries us.”

”Mexico is not a single, uniform entity, and there are many problems, for example, on the northern border (with the United States), where drug trafficking is a major presence, and a lot of journalists have begun to practice self-censorship as a way of ensuring their own survival,” Reyes told IPS.

In the four cases of the journalists killed this year, the available evidence indicates that their deaths were linked to investigative work they were carrying out. In addition, all four had reported, in different ways, that they were being threatened.

Roberto Javier Mora, editor-in-chief of El Mañana, a local newspaper in Nuevo Laredo, near the U.S. border, was stabbed to death on Mar. 19, while Francisco Ortiz, editor of Zeta, a weekly publication in Tijuana -- also on the border with the United States -- was gunned down on Jun. 22. Both murders have been attributed to drug traffickers.

On Sep. 1, Francisco Arratia Saldierna, a columnist for a number of newspapers in the Mexican border state of Tamaulipas, was found dead after having been kidnapped and tortured.

Leodegario Aguilera, editor of the magazine Mundo Político (Political World) in the state of Guerrero, was kidnapped in May, and his body was later found dumped in a ditch.

The Inter-American Press Association, a non-profit organisation which represents newspapers and magazines from Alaska to Patagonia and is dedicated to defending freedom of expression and of the press throughout the Americas, expressed its concern to the Mexican government over these killings and asked for prompt investigations.

A large number of other international organisations devoted to the freedom of expression and human rights in general have also publicised and demanded action on these cases.

In response, the Fox government called on the Mexican General Attorney's Office to investigate the murders, independently of state police agencies, who are suspected by some journalists' associations to be involved in the crimes.

Nevertheless, FAPERMEX president Rentería maintains that the government has yet to adopt any effective action to end the impunity of those who murder and continue to issue threats against journalists, and that the situation has actually worsened under the current administration.

In July, the National Human Rights Commission issued a general recommendation to the government, with particular emphasis on public prosecutors and state authorities throughout the country, to bring an end to the practice of calling on journalists to reveal their sources, ”as a means of intimidation aimed at inhibiting them from reporting the news.”

By contrast with Rentería, the directors of CENCOS and CEPET believe that there is greater press freedom in Mexico today than during the years of PRI rule, but they warn that the murders of the four journalists this year demonstrate that these rights are being weakened.

Similar views have been expressed by international organisations like Reporters Without Borders and the Latin American Federation of Journalists (FELAP).

While noting a general improvement in press freedom, they nonetheless stress that threats continue to be made against journalists in numerous states, and that some reporters are still pressured to reveal their sources, while other are sued for alleged defamation.

Up until the 1980s, most of the media outlets in Mexico expressly prohibited their reporters from criticising the government and the PRI, and the editors of most major newspapers were active members of the ruling party.