Washington ? Federal regulators opened a new front in their crackdown on offensive broadcasts Thursday, saying that almost any use of the F-word on over-the-air radio and television would be considered indecent.

The Federal Communications Commission overruled its staff and said an expletive uttered by rock singer Bono on NBC was both indecent and profane. It marked the first time that the FCC cited a four-letter word as profane; the commission previously equated profanity with language challenging God’s divinity.

The FCC on Thursday also proposed maximum fines for the broadcast of the Howard Stern radio show and for a program on two Florida radio owned by a Clear Channel Communications subsidiary.

Commissioners said they did not propose a fine for Bono’s expletive during the 2003 Golden Globe Awards because they had never before said that virtually any use of the F-word violated its rules. The FCC specifically rejected earlier findings that occasional use of the F-word was acceptable.

“Given that today’s decision clearly departs from past precedent in important ways, I could not support a fine retroactively against the parties,” said FCC Chairman Michael Powell, who had asked his fellow commissioners to overturn the agency’s enforcement bureau’s finding.

“Prospectively, parties are on notice that they could now face significant penalties for similar violations,” Powell said.

NBC did not immediately return a phone call seeking comment. A publicist for U2 said Bono was in the studio in Ireland and was not immediately available for comment.

But the decision was criticized by the Parents Television Council, a conservative advocacy group whose complaints led to the FCC’s review.

“Bono may have used the F-word as an adjective, but today’s FCC ruling turned it into a verb directed at American families,” council president L. Brent Bozell III said. He said the decision “does nothing to hold NBC accountable for this obvious breach of common-sense decency standards.”

The FCC received hundreds of complaints about the Golden Globes broadcast after Bono, the lead singer of the Irish rock group U2, said, “This is really, really, f—— brilliant.” The enforcement bureau said last October that Bono’s comment was not indecent because he did not use the word to describe a sexl act.

In another decision Thursday, the FCC proposed fining Infinity Broadcasting the maximum $27,500 for a Stern show broadcast on WKRK-FM in Detroit. The Center for Responsive Politics, a watchdog group, said fines against Stern accounted for almost half of the $4 million in penalties proposed by the FCC since 1990.