BOGOTA, May 9 (Reuters) - Colombia's president will ask the government to suspend aerial fumigation of coca plants used to make cocaine, he said on Saturday, amid signs the weed killer used may cause cancer, a decision which could complicate the country's war on drugs.
President Juan Manuel Santos said on Saturday he will ask the National Narcotics Council to suspend crop dusting flights after the World Health Organization (WHO) said in March that glyphosate they disperse is "probably carcinogenic to humans".
Colombia is one of the world's biggest producers of cocaine, which is derived from the coca plant. Its leftist rebel groups, the FARC and ELN as well as criminal gangs, make huge sums from their involvement in its production and trafficking.
"This must not from any point of view, be seen as a softening of our policy against narco-trafficking," Santos said.
"On the contrary, I have given instructions to both the Defense Ministry, police and prosecutor to intensify our work against other parts of the chain, which could even be more effective."
Santos will suggest a transition period lasting until October to shift to alternative means of eradicating the plants, including manually uprooting them, a method used increasingly in recent years while aerial fumigation has been scaled back.
Crop fumigation is backed by the United States government and carried out by U.S. contractors working in Colombia and the national anti-narcotics police, in a long-running effort to eradicate coca fields and stem cocaine production.
The Andean country's health ministry had called for the suspension of glyphosate use in light of the WHO's reclassification of glyphosate and the Constitutional Council also said a halt would be necessary if the chemical posed a risk.
Glyphosate is a key ingredient in the world's most widely used herbicide, Roundup, produced by Monsanto Co.
Monsanto says glyphosate has been proven safe for decades, and has demanded the WHO retract its claims.
Colombia is the only country in the world where plantations for drug production are targeted from the air and 1.6 million hectares have been sprayed with glyphosate in the last three decades to wipe out coca.
The government and FARC have agreed on a plan to eradicate the drugs trade in Colombia once they reach a definitive peace deal. The two sides are negotiating to end a 50 year war which has killed more than 220,000 though critics question whether the FARC and other groups will abandon the lucrative trade. (Reporting by Peter Murphy; Editing by Christian Plumb)