BOGOTA (Reuters) - Colombia’s constitutional court on Thursday upheld its own restrictions on the aerial spraying of the herbicide glyphosate to eliminate coca, the base ingredient in cocaine, but said its use could be reinstated if the government meets certain conditions.

FILE PHOTO: A peasant holds up coca leaves collected from his crops in Cauca, Colombia, January 27, 2017. REUTERS/Jaime Saldarriaga

Colombia suspended aerial fumigation with the Monsanto Co herbicide in 2015 after the World Health Organization linked glyphosate to cancer. The decision was later backed by the court, but President Ivan Duque has sought to overturn the decision because of increasing coca crops.

In a unanimous ruling, eight of the court’s judges said it will be up to the national narcotics council to decide whether spraying can restart based on conditions set out in its 2017 ruling.

The government said in a statement it respected the court’s decision and would ask the narcotics council to review its proposal to restart aerial fumigation.

In order for spraying to be renewed it is not necessary to prove with absolute certainty that the herbicide does no harm, the court said, but the council should consider all the available scientific evidence about minimizing risks to health and the environment.

Duque testified before the court in March that conditions should be modified because expansion of the crop since the restrictions began threatens efforts to consolidate peace in Colombia.

Last month a U.S. report showed cocaine output slowed for the first time since 2012. The report from the White House said the number of hectares planted with coca fell slightly in 2018 to 208,000, from 209,000, while cocaine production fell to 887 tonnes from 900.

Washington spends about $400 million annually in military and economic aid to Colombia but U.S. President Donald Trump has questioned Bogota’s ability to reduce coca cultivation, leading Duque to defend eradication efforts.

It will be “nearly impossible” for the government to meet the court’s conditions, which include continuous monitoring of health and environmental effects, and restart fumigation, said political analyst Sergio Guzman.

“This will likely be unacceptable to the U.S., and especially President Trump,” he said.

Duque has said manual eradication is more expensive and less effective than aerial fumigation and puts security forces at risk of landmines and sniper shootings.

The government says more than 66,500 hectares of coca have been eradicated and more than 330 tonnes of cocaine confiscated since he took office just under a year ago.

A 2016 peace deal between Colombia and one group of leftist rebels includes funding meant to encourage farmers to replace coca with other crops.