Colombia said on Friday it plans to legalize medical marijuana in a further shift in drug policy after suspending aerial fumigation of illicit crops.

The government is preparing a decree which would approve the therapeutic use of marijuana, the president's office said in an information sheet, and President Juan Manuel Santos told BBC Mundo the decree would be signed in the coming days.

Growing, distributing and selling cannabis will remain illegal. The South American country suspended spraying of illicit crops this year, citing cancer concerns related to the herbicide glyphosate.

Current law allows possession of up to 20 grams of marijuana or 20 marijuana plants for personal use. A recent study showed 11.5 percent of Colombians have used marijuana at least once.

The government said some companies, including foreign ones, are interested in producing and selling cannabis. There are no plans to fully legalize marijuana for recreational consumption or commercial sale, however, unlike in Uruguay, which legalized it in 2013.

Colombia, long a hub for narcotics production and trafficking, was once home to large marijuana cultivations. Much of the crop was smuggled to the United States before drug cartels began producing the more profitable cocaine.

Austria, Belgium, Canada, the Czech Republic, Finland, Israel and some U.S. states already allow medical cannabis use.

Studies show marijuana can help treat pain and nausea and offers relief for sufferers of epilepsy and other conditions.

(Reporting by Luis Jaime Acosta; Writing by Julia Symmes Cobb; Editing by James Dalgleish)