Law enforcement officials in four of the states that allow medical use of marijuana say the laws have had minimal impact on crimefighting, although they at times complicate prosecution of drug cases, a congressional report said Friday.

The report by the General Accounting Office said that only a small fraction of the people in Oregon, Hawaii and Alaska used marijuana for medical purposes. The results in California, the fourth state studied, were limited to only four counties and no statewide data was available.

Some law enforcement officials said that while crimefighting was not harmed, the laws allowing doctors to prescribe marijuana at times has complicated efforts to seize illegal marijuana or to prosecute some cases, according to the GAO report.

In some cases, law enforcement officials said the marijuana laws resulted in "a general softening" in attitudes among the public toward marijuana, the report said, and some were concerned about conflicts that arise with federal law enforcement, which still bans the drug.

The GAO examined only four of the eight states that have allowed medical uses for marijuana. The other states are Nevada, Colorado, Washington and Maine.

The GAO found that a total of about 2,450 people in Oregon, Hawaii and Alaska use marijuana for medical purposes — accounting for no more than .05 percent of the population in any of the states.

The report provided no statewide data for California. That state's law does not require medicinal marijuana users to register, although about 4,500 people have done so voluntarily in four of the state's 58 counties, according to the GAO.

In Northern California, Humboldt County officials said marijuana growers are allowed to grow hundreds of plants while claiming to be a medical caregiver to multiple patients, and no documentation is required.

Some local law enforcement officials in California questioned how effectively they could prosecute criminal marijuana cases since the state has no limit on the amount of marijuana that can be held by a patient or a caregiver.

While the other three states have established limits, some law enforcement officials said they too were less likely to pursue cases that could be shielded by the provisions.

The Bush administration disagreed with some of the report's findings.

The state marijuana laws have resulted in a "worsening of relations between federal, state and local law enforcement," Acting Assistant Attorney General Robert F. Diegelman wrote the review of the report.

The laws create "legal loopholes for drug dealers and marijuana cultivators to avoid arrest and prosecution," he said.

Data from the three states that require registries — Oregon, Hawaii and Alaska — showed that over 70 percent of medicinal marijuana users from each state were at least 40 years old.

In Hawaii and Oregon, where information on gender was kept, about 70 percent of users in each state were male, according to the report.

Both states also showed most of their patients were taking marijuana to treat severe pain and persistent muscle spasms. Such information was not available for Alaska or California.

The GAO conducted its study from September 2001 to June 2002.