Attorney General Dick Thornburgh took the occasion of the swearing in of a new administrator for the Drug Enforcement Administration yesterday to deliver some of his most forceful comments to date about the role that casual cocaine users play in fueling the nation's drug crisis.

Five days after one of his former top aides, Henry G. Barr, was indicted on cocaine charges, Thornburgh said the drug problem "affects every American and it affects each of us in various ways."

As an example, Thornburgh cited a recent study that he said showed that 64 percent of every violent crime has either a perpetrator or victim who was using drugs or alcohol. "This indicates there is a straight-line relationship between the ravages of violent crime in our communities and the abuse of drugs," he said during a brief speech at DEA headquarters.

Thornburgh then added: "There is indeed a straight-line relationship between every coke sniffer and every crack smoker in this country and the carnage and murder that takes place within our inner cities and within all our communities."

Thornburgh, who last week called Barr's indictment a "personal tragedy," has declined further comment on the matter. Barr's lawyer last week attacked the Justice Department for indicting his client, in part because the case involved relatively minor cocaine possession charges. Barr had been one of Thornburgh's closest aides for nearly 20 years, serving most recently as his special assistant for criminal investigations.

Asked if Thornburgh's comments yesterday were intended as a reference to the Barr case, the department's communications director, David R. Runkel, replied, "You'll have to draw your own conclusions."

Following Thornburgh's talk, new DEA Administrator Robert C. Bonner picked up on the same themes, saying, "Americans are finally reaching the conclusion that there is no such thing as a casual or recreational drug user."

Bonner, 48, a former U.S. attorney in Los Angeles, resigned this week as a federal judge to take the DEA job.