The Federal Communications Commission yesterday released an audit of 30 radio and television stations throughout the country that showed that political candidates are regularly overcharged for their advertising.

The report, based on a review of billings at stations in five states, found that 80 percent of the TV stations and 40 percent of the radio broadcasters failed to give political candidates the lowest available rates, as required by federal law.

The audit found overcharging in almost every program time period analyzed and cited instances when political candidates paid almost double what commercial advertisers paid.

Although the FCC will not levy any sanctions on the stations because of the informational purpose of the report, violations of the law regarding campaign advertising can result in fines of up to $250,000.

The agency said it will launch an educational campaign next week to inform station executives regarding political advertising laws.

Roy J. Stewart, chief of the FCC mass media bureau, said broadcasters generally want to comply with the laws but are not aware of the full range of their responsibilities.

According to the FCC report, "political candidates have paid higher prices than commercial advertisers because sales techniques encouraged them to buy higher-priced classes of time."

Milton O. Gross, chief of the FCC political programming branch, explained that the stations failed to advise the candidates of the lowest advertising rates available, which are usually given to businesses that advertise heavily.

Stations contend that although they offer cut rates to political candidates, many campaigns reject the "lowest available rate" because it involves the possibility of getting bumped from key spots if full-priced advertisers come along.

Harriet Yellin, a media buyer based in Boston who arranged time for Massachusetts Gov. Michael Dukakis's presidential campaign, acknowledged that some political campaigns are willing to pay a higher rate to ensure that their ads will run at key times, such as just before or after news programs. She said that how each station deals with the laws regarding political advertising is "subject to different interpretations."

But Gross explained that many stations negotiate lower rates with key customers that also carry guarantees that the ads will run -- deals, he said, that should also be offered to politicians.

Harrison Hickman, a Washington pollster and election expert, said that the commitment of stations to public service is not very high.

"Political advertising is a way to make money, not a way to contribute to public service," he said.

The audit showed that candidates fared better on radio -- only four out of the 10 stations audited had overcharged political candidates.

Brooke E. Spectorsky, station manager of the San Francisco-based KTVU-TV, one of the audited stations, responded to the FCC report tersely. "We follow FCC rules to the letter," he said.

Other stations contacted for reaction yesterday declined comment.

Meanwhile, Sen. John C. Danforth (R-Mo.) took the occasion of the FCC audit to tout legislation that would prevent stations from bumping political advertising, even those paying the lowest rate.

"If we are serious about stopping the so-called 'money chase' by politicians, Congress should enact the bill approved by the Senate Commerce Committee," Danforth said. "This proposal would apply to federal and nonfederal races across the board and ensure that candidates pay the same prices charged to major commercial advertisers."

Edward O. Fritts, president of the National Association of Broadcasters, called upon the FCC to further explain the laws to broadcasters. "Historically the commission has not done a good job of educating broadcasters to the various nuances in this important area," he said.

He added, however, that "it is unfortunate that the commission has issued a report which gives the impression that it has made final conclusions when it has not and that presumes there are violations when broadcasters have not had an opportunity to respond to the commission's findings. We think what this report does is add more misunderstanding and confusion to a subject rife with difficult interpretation."