BOGOTA, Colombia (AP) _ President Andres Pastrana accused the United States of mishandling a drug bust on a Colombian air force plane, saying U.S. officials should have told his government before the plane took off from Colombia that it carried illegal narcotics.

Customs officials at the international airport in Fort Lauderdale, Fla., said Tuesday that they found 1,639 pounds of cocaine and 13 pounds of heroin hidden aboard the C-130 aircraft and detained the six-man crew.

``Why, if they knew about this cargo ... didn't they tell us first?'' Pastrana said in his first public comments on the incident, which has been an international embarrassment for his 3-month-old administration.

Pastrana also questioned why U.S. authorities seized the plane at the Florida airport, rather than trying to gain more information by tracking the shipment to its final destination.

A spokesman for the U.S. Customs Service in Miami, Mike Sheehan, told The Associated Press that the drugs were discovered in ``a routine inspection, like those we have conducted many times in the past.''

The plane's six-man crew was released Monday after questioning turned up no leads. ``We could make no association between them and the drugs,'' Sheehan said.

``We're truly sad that an incident like this once again blemishes the image of an entire country,'' said Pastrana, who took office vowing to step up Colombia's fight against drug trafficking.

In Colombia, the seizure has led to multiple arrests and a command shakeup in the 12,000-member air force.

Federal prosecutor's agents on Thursday detained six air force members, including Maj. Gonzalo Noguera, the intelligence chief of the Bogota military airport from which the plane took off, as well as a lieutenant and four aviation technicians.

Noguera and two other officers were forced into retirement. Air force commander Gen. Jose Manuel Sandoval resigned.