The United Nations says Peru has overtaken Colombia as the main producer of coca leaf, the raw material for making cocaine.
The UN Office on Drugs and Crime (UNDOC) says a steady fall in Colombian production over the past decade shows that the drug control policies of the government there are paying off.
But it says it is worried by the increase in Peru, where coca production has doubled over the past decade: more than 45% of the world's supply now comes from Peru, compared with 39% from Colombia.
Coca cultivation in Colombia has fallen nearly 60% since the peak of a decade ago, according to UNDOC estimates, the BBC reports.
In Peru over the same period it has increased by 55% - though UNDOC says that's still half what it was two decades ago.
Critics say war on drugs is futile
Peru was the world's biggest coca producer until the mid-1990s, when production shifted to Colombia as the security situation in Peru improved.
Critics of the US-led drugs control policy say the ability of traffickers to transfer their operations from one country to another shows the futility of the war on drugs.
There was little change in the scale of cultivation in Bolivia, the third biggest producer, which accounts for 15% of world production.