BOGOTA (Reuters) – Potential production of pure cocaine hydrochloride in Colombia was up by 1.5% last year to 1,137 metric tonnes, the United Nations Office on Drugs and Crime (UNODC) said on Wednesday, even as the areas planted with primary ingredient coca decreased.

Despite decades of anti-narcotics efforts, Colombia remains one of the world’s top cocaine producers. Leftist rebels, crime gangs and former right-wing paramilitaries are all involved in production and transport to consumers based largely in North America and Europe.

The area planted with coca fell 9% in 2019 to 154,000 hectares (381,000 acres) from 169,000 hectares the year before, the UNODC said. Potential cocaine output was 1,120 metric tonnes annually last year.

The increase in productivity is due to the concentration of coca growing in specific areas, UNODC representative Pierre Lapaque said in a joint presentation with Colombian President Ivan Duque.

“Colombia continues forward, confronting this phenomena and also continuing to confront the organized armed groups that feed off and are fueled by illicit economies,” Duque said.

Some 18% of the country’s coca is planted in forest reserves and about 16% on territory belonging to Afro-Colombian populations, Lapaque said.

Areas of voluntary eradication are at much lower risk of re-planting, Lapaque told Reuters by phone, compared with areas where forced eradication is carried out by security forces.

“On one hand it’s between 40% and 50% re-planting and on the other it’s less than 1%,” he said.

The UNODC numbers were below recent estimates from the U.S. government, which says coca cultivations cover more than 200,000 hectares (494,211 acres). Duque has come under repeated pressure from the U.S. Trump administration to increase eradication.

Duque backs the re-introduction of aerial fumigation with glyphosate, which was suspended in 2015 after the World Health Organization said the herbicide could potentially cause cancer.

Duque’s administration is working to meet health and environmental requirements demanded by the Constitutional Court before aerial fumigation can restart.