Mexico's president, Felipe Calderón, has joined calls for a debate on the legalisation of drugs as new figures show thousands of Mexicans every year being slaughtered in cartel wars.

"It is a fundamental debate," the president said, belying his traditional reluctance to accept any questioning of the military-focused offensive against the country's drug cartels that he launched in late 2006. "You have to analyse carefully the pros and cons and key arguments on both sides." The president said he personally opposes the idea of legalisation.

Calderón's new openness comes amid tremendous pressure to justify a strategy that has been accompanied by the spiralling of horrific violence around the country as the cartels fight each other and the government crack down. Official figures released this week put the number of drug war related murders at 28,000.

Until recently the government regularly played down the general impact of the violence by claiming that 90% of the victims were associated with the cartels, with the remainder largely from the security forces. In recent months it has started to acknowledge a growing number of "civilian victims" ranging from toddlers caught in the cross fire to students massacred at parties.

Momentum behind the idea that legalisation could be part of the solution has been growing since three prominent former Latin American presidents signed a document last year arguing the case.

César Gaviria of Colombia, Fernando Cardoso of Brazil and Ernesto Zedillo of Mexico urged existing governments to consider legalising marijuana as a way of slashing cartel profits.

This year Mexico's national congress began a debate on the possibility that resurfaced again this week during a series of round table discussions between the Calderón, security experts, business leaders and civic groups.

The "Dialogue for Security: Evaluation and Strengthening" is part of a new government effort to counter the growing perception in Mexico that the president's drug war strategy is a disaster.

"I'm not talking just about legalizing marijuana," analyst and write Hector Aguilar Camin said during the Tuesday session, "rather all drugs in general."

After accepting the need to directly address the proposal, Calderón made it clear he did not support it. "It requires a country to take a decision to put several generations of young people at risk," he said, citing a likely increase in consumption triggered by lower prices, greater availability and social acceptability.

He added that the predicted "important economic effects by reducing income for criminal groups" would be limited by the integration of Mexican drug trafficking into international markets where drugs remain largely underground.

Calderón did not mention current moves to soften drug laws in the US, including a planned vote in California in November on an initiative that would allow marijuana to be sold and taxed. Nor did he address the home grown argument that legalisation would remove the roots of the violence raging in the country.

"Legalisation would render the war pointless as drugs would become just another product like tobacco or alcohol," Jorge Castañeda, a legalisation advocate and former foreign minister, told W Radio. He added that even if it did prompt an increase in drug use. "It is worth considering whether this is preferable to having 28,000 deaths."

The new death toll, which was not broken down, is significantly higher than the informal counts kept by newspapers. Milenio newspaper put the number of drug-related deaths in July at 1,234.

Some leading critics of Calderón's strategy, however, do not believe legalisation is the key to reining in the cartels and the violence, preferring to emphasize the need to increase efforts to go after money laundering and political corruption.

Edgardo Buscaglia, and expert in organised crime around the world, argues that the recent diversification of the Mexican cartels into other criminal activities ranging from systematic extortion to people trafficking would give them ample reason to keep fighting each other, even if drugs were legal. "Legalising drugs would be good public policy," he said, "but it would not be a tool with which to combat organized crime."