WASHINGTON — An estimated 2,900 Maine residents are hard-core cocaine addicts who use the drug at least once a week, according to a new study released Thursday by the Senate Judiciary Committee.

On a per-capita basis, though, Maine ranked fifth lowest among the states based on populations of addicts.

The authors of the study conceded that their estimates about drug usage in rural states may be understated because law enforcement and drug rehabilitation agencies are stretched thin by geographic distances.

Nationwide, the Senate study concluded that nearly 2.2 million Americans are addicted to cocaine, a projection that is three times larger than the estimate cited by the Bush administration in its war on drugs.

Although the population of cocaine addicts appears to have risen dramatically, casual use of the drug has declined sharply during the past five years, according to the report.

The Senate committee’s findings, which were compiled by Harvard University’s Kennedy School of Government, will stir continued debate about the strategy and objectives of the nation’s war against drugs.

Sen. Joseph Biden, D-Del., who is chairman of the Senate Judiciary Committee, claimed that hard-core users should be the primary target of the U.S. anti-drug crusade, while national drug policy director William Bennett has advocated that efforts be directed mainly at stemming casual cocaine use.

The new Senate report raised doubt about the official findings of the National Institute on Drug Abuse’s household survey, which estimated the number of Americans who use cocaine at least once a week at fewer than 900,000.

Bennett’s anti-drug strategy is based on the inaccurate 900,000 projection of hard-core addicts, Biden said.

“How could fewer than 900,000 bring such havoc to a nation of 250 million?,” the Senate report asked.

State officials who are involved in Maine’s war against drugs said they were not surprised by the study’s estimate of 2,900 Maine cocaine addicts, but said they had no way of evaluating its accuracy.

“(That) does not seem like a high number to me,” said David Faulkner, the director of Day One, a Portland-based substance abuse treatment facility.

Sylvia Lund, who heads the state Office of Drug Abuse and Alcoholic Prevention, said Maine officials have few accurate statistics to measure cocaine abuse, but believes that the state’s stepped up criminal prosecution of drug users may have begun to deter casual users.

“By arresting more people and making examples of them, those who are not strongly addicted may choose not to use the substance,” Lund said.

U.S. Attorney Richard Cohen, the leading figure in Maine’s war against drugs, agreed with the Senate study’s premise that the casual use of cocaine is declining, even as the population of hard-core addicts increases.

Faulkner, however, said his counselors saw no evidence of such a decline in the casual use of cocaine among Maine residents.

“We’ve actually seen a fivefold increase in cocaine use since 1984. Today, just about every person who comes in to be treated (for substance abuse) indicates that they have been involved with cocaine,” Faulkner said, adding that during the mid-1980s only one in four or five of Day One clients told of using cocaine.

At a press conference Thursday, Biden said the finding that nearly one out of every 100 Americans is a weekly cocaine user “is as alarming as it is tragic.”

“(This) suggests that we have a hard-core addict problem that is far worse than virtually every previous estimate of its scope,” said Biden, who called for a “massive new effort” to deal with the problem that would include increased federal aid to cities hardest hit by the drug problem, building new prisons with drug treatment facilities, doubling state and local law enforcement grants, and expanded research on medicines to treat drug abuse.

Biden estimated the cost of such a program at $3 billion.