BOGOTA, Colombia (AP) — Colombia's police could start using drones to tackle a five-year surge in cocaine production that has jeopardized relations with the United States.

State contracting documents show that anti-narcotics police in the South American country have hired a local company to test drones for spraying herbicides on fields of coca, the base material for cocaine.

The remote-controlled devices would be expected to eradicate 8 hectares (20 acres) of coca a day. Coca cultivation has doubled in Colombia since 2012 and now exceeds 188,000 hectares, according to U.S. estimates.

Three years ago Colombia decided to ban the aerial spraying of coca crops over environmental and health concerns. But drones fly at lower altitudes than spray planes and are expected to have a smaller environmental impact.