"To suggest liberalisation, allowing consumption, production and trafficking of drugs without any restriction whatsoever, would be, in my opinion, profoundly irresponsible ... If we accept regulations for alcoholic drinks and tobacco consumption and production, why should we allow drugs to be consumed and produced without any restrictions?"
He insists, however, that prohibition has failed and that an alternative must be found.
Polls suggest the vast majority of Guatemalans oppose decriminalisation, but Perez Molina's comments will be studied closely by foreign policy experts who detect that Latin American leaders are shifting their stance on prohibition after decades of drugs wars that have left hundreds of thousands dead.
Mexico's President, Felipe Calderon, has called for a national debate on the issue. Last year Juan Manuel Santos, Colombia's President, said that if legalising drugs curtailed the power of organised criminal gangs who had thrived during prohibition, "and the world thinks that's the solution, I will welcome it".
Latin America's increasing hostility towards prohibition makes Obama's attendance at the summit potentially difficult. The Obama Administration, keen not to hand ammunition to opponents during an election year, will not want to be seen to be as softening its support for prohibition. However, US Vice-President Joe Biden has acknowledged that the debate about legalising drugs was now "legitimate".
Fernando Henrique Cardoso, former president of Brazil and chairman of the global commission on drug policy, has said it is time for "an open debate on more humane and efficient drug policies".
- Observer