President Hugo Chavez's insistence that Venezuela doesn't need U.S. help in fighting drug trafficking is raising diplomatic tensions as American officials warn of a surge in cocaine flights out of the country.

Hugo Chavez AP PHOTO

New surveillance estimates released by U.S. counterdrug officials say there has been a more than 16-fold increase in the amount of cocaine departing Venezuela by air since 2002. They say that rise — combined with a doubling of smuggling by sea — pushed the estimated flow of Colombian cocaine through Venezuela to 256 metric tons last year, four times higher than in 2004.

But Chavez dismisses the estimates as an attempt to discredit his government and has rebuffed U.S. offers of help.