A US official has publicly accused Britain of failing to take action to eradicate a massive crop of Afghan opium poppies.

"Our point of disagreement, and I put it very directly is that we believe that if there is a heroin poppy that needs to be eradicated, we shouldn't be picking and choosing, we shouldn't be delaying, waiting for an alternative revenue stream to become available," Robert Charles, the assistant secretary of state for international narcotics and law enforcement, told Congress.