While drug abuse shows some signs of leveling off in the United States, narcotics traffickers are increasing their exports to Western Europe and opening new smuggling routes and markets in the Soviet Union, Eastern Europe and Africa, according to a United Nations report released yesterday.

The report warns that the political turmoil within the former Soviet Bloc and a relaxation of controls have created an emerging drug threat that must be met by strong "countermeasures" by the international community.

In the past two years, it states, there has been a sharp increase in seizures of heroin moving through Czechoslovakia, Hungary and Romania and a near doubling of reported drug addiction in the Soviet Union.

The report by the U.N. International Narcotics Control Board is the latest in a series of warnings from anti-drug agencies about the increasing economic integration of the international drug business. It also underscores complaints among some anti-drug officials and members of Congress that reported declines in drug use among the middle class have caused undue complacency within the Bush administration, especially in light of record production of drug crops and the expansion of trafficking routes overseas.

"Trafficking organizations, often in conjunction with terrorists, continue to forge links within countries, within regions and inter-regionally," the report states. "The response of the international community to the traffickers must be even more forceful, more comprehensive, more innovative."

Rep. Charles B. Rangel (D-N.Y.), chairman of the House Select Committee on Narcotics Abuse and Control, said the U.N. study contrasts with recent assertions by the Bush administration of progress against drug abuse. "While we hear calls of victory from the White House, we hear calls for help from the world," Rangel said.

A common theme of the report is the resiliency and adaptability of drug traffickers.

New controls on U.S. exports of precursor chemicals used to manufacture cocaine in South America have led to a surge in the shipment of such chemicals from Western Europe. A crackdown by the Colombian government has prompted that country's cocaine cartels to move growing operations into remote Amazon regions of Brazil and to set up new production facilities in Ecuador.

As a result, the report states, Ecuador has emerged as a "crucial transit point" for drugs and precursor chemicals with an estimated 35 to 50 tons of cocaine moving through the country annually.

The report also warns of growing evidence that the South American cartels have developed "joint venture" operations with European criminal organizations -- a reference to the Mafia -- to smuggle cocaine to Europe and heroin to North America.

The cartels at the same time are establishing ties with Southeast Asian gangs that are increasingly supplying the international heroin market, it said.

Betty C. Gough, a former U.S. diplomat who is president of the narcotics control board, called these linkages a "troubling development," adding that "the cartels are joining forces in a sort of world network."

Another disturbing development, she said, is the cartels' increased trafficking in sophisticated weaponry. She noted that the report concludes that nations where such guns are manufactured, such as the United States, bear a "heavy responsibility" for keeping them out of the hands of traffickers.

Gough said that while the report's overall tone is "somber," there is reason for cautious optimism. "There appears to be some indications of improvement . . . of declines of abuse" in the United States and some other Western nations, she said. "The question is, how long will it hold up?"