A new U.N. study finds that cultivation of the leaf used to make cocaine skyrocketed last year. The report is likely to raise questions about the government's decision to abandon aerial eradication efforts.

The UN's survey found that coca production jumped 44 percent last year to about 266 square miles (69,000 hectares).

The increase is the biggest in years and confirms a trend identified in a U.S. government survey published two months ago.

President Juan Manuel Santos in May decided to halt fumigation of coca crops that has been the cornerstone of the US-led drug war in Colombia for decades. The decision came in the wake of a report by a research arm of the World Health Organization classifying the herbicide used to destroy coca as a probable carcinogen.