The U.S. report said that Venezuela, Bolivia and Myanmar "failed demonstrably" in the effort over the past year and kept them on Washington's drug trafficking "black list." The report said that Venezuela remains a preferred route for drugs leaving South America and noted that senior Bolivian officials have been arrested for facilitating shipments.

Both countries, which are led by leftist presidents highly critical of U.S. foreign policy, lambasted the report, denying its claims and saying that Washington has no right to judge other countries on how they handle the drug trade.

A statement from Venezuela's Foreign Ministry said it lamented that Washington "insists on mining the ground of bilateral relations with the publication of this type of document."

Bolivian President Evo Morales accused the U.S. of using the war on drugs for political purposes.