U.S. Drug Enforcement Administration officials say that they prefer to catch American drug traffickers outside the United States because of greater likelihood they would be prosecuted according to interviews with American agents here and the Mexican attorney general.

One U.S. agent who has been stationed here said drug cases had "less chance of being thrown out of court" when offenders are caught outside the United States.

The Americans want us to catch them here", Mexican Attorney General Oscar Flores said. "They say we crack down harder".

As a second group of 60 American prisoners flew from Mexico to the United States today, U.S. and Mexican officials were insistent that their joint campaign against narcotics trafickers would not be weakened by the new treaty which allows American drug offenders to serve shorter terms at home.

Some experts are nevertheless concerned that early release of Americans convicted in Mexico removes the teeth from Mexico's much stiffer prison sentences for all but minor drug offenses.

The Mexican authorities are unhappy with reports of a large-scale early release of the transferred convicts. They are aware that under U.S. law, some 60 Americans are due immediately for mandatory release, while most others are expected to get a sympathetic hearing from parole boards leading to freedom.

"This is contrary to the spirit in which the treaty was negotiated" said on well-placed Foreign Ministry source here. "If most of the Americans are freed up there, take my word for it that we are going to release the Mexicans transferred here from the U.S."

A massive early release would also appear to contradict the objective of the U.S. Drug Enforcement Administration which over the past eight years has worked closely with the Mexicans to ensure American arrests.

Mexico has tried to reduce the controversy about the prisoner issue through an order that no charges be pressed against marijuana users caught with small amounts, presumably for personal use. As a result, in the last six months, close to 50 Americans have been handed over to U.S. consular offices and deported promptly to the United States.