Latin American drug traffickers suffered severe blows in 1990 but, like businessmen in a recession, they showed their resilience by rebuilding, changing methods and seeking new markets, officials and diplomats say.

When a government crackdown made life difficult in Colombia, the country's powerful drug cartels - which supply 80 percent of the cocaine consumed in the United States - switched some cocaine laboratories to neighboring countries, police say.With U.S. demand apparently peaking, the traffickers sought new markets in Europe and Japan.

To beat official vigilance, the traffickers use ever more sophisticated methods to smuggle cocaine and constantly change routes. Vast profits make it easier to corrupt officials and give traffickers an incentive to find a way around any obstacle placed in their path.

"Drug trafficking today is the most profitable illegal business in the world, posing the greatest threat to humanity," a recent report by Colombia's Administrative Department of Security - the security police - said.

"Although all countries have increased their dedication to trying to control this terrible scourge, the supply of illicit drugs continues to far exceed demand," it said.

Drug abuse, rated by Americans as their number one problem earlier this year, has slipped down the U.S. agenda, overshadowed by domestic economic woes and the Persian Gulf crisis.

President Bush has claimed progress in the war on drugs in the United States, citing a survey showing cocaine use down by 45 percent compared with 1988. But political opponents were skeptical.

The most dramatic battleground of the drug fight - the all-out war between Colombia's cocaine cartels and the state - changed radically after new President Cesar Gaviria took office in August.

Drug traffickers detonated many bombs in Colombia in the first half of 1990, killing scores of civilians and murdering officials, judges and more than 250 police officers.

Colombian police and soldiers smashed cocaine laboratories, confiscated aircraft and property suspected of belonging to traffickers, arrested or killed some middle-level traffickers and seized a record 50 tons of cocaine in 1990.

Most of the big names, like Medellin cartel leader Pablo Escobar, escaped, although Fabio Ochoa, another leader of the cartel, surrendered last week.

The war died down when Gaviria adopted a new policy, trying to tempt traffickers into surrendering by offering to waive extradition to the United States and to cut jail terms.

A U.S. official said cocaine production in Colombia dropped by about a quarter after the August 1989 crackdown but was now almost back to the pre-crackdown level.