BOGOTA, Colombia (AP) -- Colombia's government plans to legalize the cultivation and sale of marijuana for medicinal and scientific purposes, officials said Thursday in a surprise shift by the longtime U.S. ally in the war on drugs.

The change is coming in an executive decree that President Juan Manuel Santos will soon sign into law. It will regulate regulating everything from licensing for growers to the eventual export of products made from marijuana, Justice Minister Yesid Reyes said.

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With the new policy, Colombia joins countries from Mexico to Chile that have experimented with legalization or decriminalization as part of a wave of changing attitudes toward drug use and policies to combat it in Latin America. But unlike many of its neighbors, Colombia has long been identified with U.S.-backed policies to eradicate drug production and a sharp decline in levels of violence over the past 15 years is largely attributed to the no-tolerance policing.

Sen. Juan Manuel Galan, who last year introduced legislation that tracks with the government's decree, said that as many as 400,000 Colombians suffering from epilepsy and other ailments could benefit from the clearer regulatory framework to be provided by the decree.

See Colombia's marijuana supporters:



12 PHOTOS Marijuana Supporters in Colombia See Gallery Colombia to legalize commercial sale of medical marijuana A man smokes marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) men prepare marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) Artists perform during a demo for the legalization of marijuana in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) People demonstrate for the legalization of marijuana in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) A man smokes marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) People demonstrate for the legalization of marijuana in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) A man smokes marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) A man smokes marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) Men prepare marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) A woman smokes marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) A man smokes marijuana during a demo for its legalization, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) A person wears a Guy Fawkes mask during a demo for the legalization of marihuana, in Medellin, Antioquia department, Colombia on May 2, 2015. The demo is against drug trafficking and for the self-cultivation for medicinal and recreational purposes. AFP PHOTO/Raul ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

Colombians for two decades have been allowed to possess small quantities of any narcotic for personal use thanks to a series of Constitutional Court rulings guaranteeing the "free development of one's personality."

But the congress and the executive branch have been loath to endorse such views, in part because of officials' skittishness about showing any weakness in a country that is the biggest supplier of cocaine to the U.S.

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Indeed, conservative critics in Colombia and abroad see Santos' drive to reform drug policy, including a decision earlier this year to end a two-decade-old campaign of spraying illegal coca crops with herbicides, as a sign that the government's resolve is weakening.

Reflecting those concerns, officials went to great lengths Thursday to explain that they are not looking to further liberalize recreational use of marijuana as was recently done in Uruguay, the region's pioneer in drug policy reform.

"Nobody is talking about legalizing anything except for these two purposes," Reyes said.

Colombia gained international fame since the 1970s as a producer of potent pot strains such as Santa Marta Gold. Health Minister Alejandro Gaviria told Blu Radio that he envisions Colombia positioned as a major global player in the booming market for marijuana products.

"Our phones are ringing off the hook as we get ready for the next chapter," said a statement from John Campo, president of the parent of the U.S.-owned Sannabis company, which is developing cannabis-based oils, creams and other products on a self-governed indigenous reservation in southern Colombia.

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