Former Mexican president Vicente Fox has called for the legalisation of drugs, arguing that prohibition has failed to curb rising drug-related violence and corruption.
Mr Fox said legalisation did not mean that drugs were good.
But he said it was a strategy that could reduce the power of the cartels.
The current Mexican president, Felipe Calderon last week called for a debate on legalisation, but he said he personally opposed the idea.
More than 28,000 people have died in drug-related violence since Mr Calderon took office and deployed the army to fight the cartels.
Vicente Fox was also a supporter of the US-led campaign against drugs when he was president from 2000 to 2006.
He and Mr Calderon both belong to the conservative PAN party.
But writing on his blog, Mr Fox said the cost of of the war had been "enormous" for Mexico.
As well as the loss of life, the conflict had damaged Mexico's international image and economy, and had consumed vast resources that could have been used for other things, he argued.
"We should consider legalising the production, sale and distribution of drugs," he wrote. "Radical prohibition strategies have never worked."
"Legalisation does not mean that drugs are good," Mr Fox added.
"But we have to see it as a strategy to weaken and break the economic system that allows cartels to make huge profits, which in turn increases their power and capacity to corrupt."
Mr Fox also criticised Mr Calderon's decision to deploy the Mexican army to fight the cartels, saying it had damaged their image and exposed them to human rights violations.
"They are not prepared for police work," he argued. "They should return to the barracks."
President Calderon called last week for a debate on the legalisation of the drug trade.
But he has stressed that he himself was against the idea.
While legalisation would reduce the financial power of organised crime, he said in an interview with Colombia's radio Caracol on Sunday, it would also make drugs much cheaper, leading "millions and millions" more people to take drugs.
Mr Calderon insisted he would continue his military-led campaign against the cartels despite rising violence, saying that Colombia had provided a useful example.
"When Colombia decided to confront the criminals with determination, crime began to retreat and the state began to win," he said.
Mr Fox's support for drugs legalisation puts him alongside other former Latin American presidents who have called for a new approach to the problem.
in 2009, Fernando Henrique Cardoso of Brazil, Cesar Gaviria of Colombia and Ernesto Zedillo of Mexico jointly argued that prohibition had failed.