Clear Channel Communications has returned fire at radio shock jock Howard Stern, escalating a war over obscenity between the two parties.

The radio conglomerate filed a $3 million countersuit yesterday against Stern's company One Twelve Inc. and his show's distributor, Infinity Broadcasting, claiming that Stern violated his contract by knowingly airing indecent material on the show that was not in compliance with federal law and FCC regulations.

"We simply aren't willing to put the future of our radio station licenses in the hands of Mr. Stern or Infinity," Andy Levin, Clear Channel's chief legal officer, said in a statement. "Fortunately, our contract doesn't require us to do that."

The countersuit comes less than a month after Infinity and One Twelve filed a $10 million lawsuit against Clear Channel for yanking the Stern show off six of its stations last winter, saying the company dropped Stern improperly and owed them license fees.

In February, Clear Channel, citing a new zero-tolerance policy toward indecency, dropped Stern in Fort Lauderdale, Orlando, Louisville, Pittsburgh, San Diego and Rochester after the host graphically discussed a pornographic video during his show.

"The radio show was pulled because Mr. Stern and Infinity refused to assure us that future programs would conform to the law," Levin said in the same statement. "That was a key term in the agreement, and we gave them every opportunity to make good on their word before we permanently retired the show."

Clear Channel has since paid $1.75 million to clear all indecency fines prompted by Stern and other radio broadcasters and to settle pending investigations.

An Infinity spokesman declined to comment and Stern's agent Don Buchwald could not be reached yesterday.

Despite the fines, Infinity launched Stern's show last month in nine additional cities, including four markets where he was dumped by Clear Channel.