President Enrique Peña Nieto's decision not to attend a three-day special session on drug policy at the United Nations' General Assembly next week is a sign of his reluctance to seriously address a key issue for Mexico, according to decriminalization activists.

"The president is putting his head in the sand," said Lisa Sánchez of the pro-legalization group Mexico United Against Crime. "The government is sending worrying signals that it is not interested in the issue of drugs. The cancellation of the president's participation is another sign that he doesn't care and doesn't want to debate, and doesn't want to take a stand."

Peña Nieto's apparent qualms over seeking a leading role at the special session — which states its goal as the development of an "integrated and balanced strategy to counter the world drug problem" — looks, at least, a little odd.

Mexico has an obvious interest in any discussion of international drug policy, not least because of more than 100,000 deaths attributed to the country's drug wars since the government launched a major crackdown on organized crime almost a decade ago.

The need to explore other ways of controlling the cartels was widely seen as being behind Mexico's decision, in 2012, to join Colombia and Guatemala in proposing that the special session, known as UNGASS, be brought forward from its original date in 2019.

UNGASS, due to start on April 19, is also taking place at a time when Mexico is supposed to be in the midst of a paradigm-shifting national debate on drug policy triggered by a landmark supreme court ruling on marijuana in November last year.

That ruling permitted four individuals the right to cultivate and consume the drug in any way they feel like. Four more similar rulings would require the Mexican congress to approve legislative reforms that provide these rights to all citizens.

Peña Nieto responded to the November ruling by launching a "national debate" on the issue with great fanfare. At the time he said that he personally opposed legalization, even stressing that he would never allow his own children to smoke a joint in his presence. He added, however, that he was open to having his mind changed by the debate.

Since then the interior ministry has organized public fora in five cities around the country titled "the national debate on the use of marijuana."

The formal conclusions of these discussions are due to be presented by the ministry to congress next week, probably on April 21, the day UNGASS winds up.

Statements made by interior minister Miguel Angel Osorio Chong suggest that these will revolve around a proposal to increase the threshold of the amount of marijuana an individual can legally possess from the current five grams, as well as measures to permit consumption of the drug for medical purposes.

In an interview last month, Luis Alfonso de Alba, Mexico's chief diplomat on matters of narcotic policy, confirmed that these would be the likely core of Mexico's proposals at UNGASS.

Sánchez, the activist from Mexico United Against Crime, is not impressed. She complains that the government ensured the debate was "tepid and fearful" by seeking to limit it to generalities that "would have been innovative in the 1970s" but, in today's climate, seemed like "a debate over the fact that the sun exists."

At the same time, however, she applauds a more rounded proposal to legalize marijuana for medical and scientific purposes, as well as for fun, presented to the Senate last week by conservative senator Roberto Gil. The proposal, which her organization helped write, gives the state a monopoly on the purchase of marijuana from legal and regulated producers, as well as the sale to consumers.

There are also signs that some sectors of the federal government are at least contemplating the idea of legalizing the cultivation of opium poppies for use in the production of morphine-based medications that are hard to obtain in Mexico.

Last month the governor of the beleaguered southern state of Guerrero floated the idea. A couple of weeks later the news magazine Proceso published information from an internal government report exploring the possibility.

How much, if any, of these bolder initiatives will make it into Mexico's participation in UNGASS is still not known. What is now clear, however, that they will not be made by Peña Nieto who has yet to give any explanation of his decision to stay away from the meeting.

The Mexican delegation will now be headed by foreign minister Claudia Ruiz Massieu who spoke to reporters about UNGASS while accompanying the president on a tour of Germany this week, just before he became the first Mexican president to visit Denmark since 1827.

"Mexico will be at the General Assembly like all the other countries," Ruiz Massieu said. "Mexico will make its position known with firmness and lots of clarity."

The message received by many in Mexico, however, is that the president would prefer not to be directly associated with the international debate on drug policy in New York.

"Giving up the chance to use this forum with clarity and courage diminishes Mexico," prominent author and political commentator Héctor Aguilar Camín wrote this week in the newspaper Milenio. "Mexico is one of the few countries that has the moral authority and experience required to talk with deep knowledge in the UN Assembly about its costly crusade that gets ever more absurd and unacceptable to the world's citizens."

One of the few to come to Peña Nieto's defense has been right-wing crime analyst José Antonio Ortega, who opposes the legalization of weed because of its "very serious" health impacts.

"At the moment there is no clear definition of what the country is going to do or what we Mexicans want," he said both of marijuana and wider liberalization of drug policy. "The [debate] is still going on and until we have a clear result, the president would not have the support needed to take a position."