Authors and publishers of two forthcoming books on U.S. intelligence said yesterday that Central Intelligence Agency Director William J. Casey has warned them that he believes they could be violating the law if their books include any secret "communications intelligence."

Casey issued the first warnings in telephone calls placed to the writers within the same few minutes last Thursday afternoon. He called Bob Woodward, an assistant managing editor of The Washington Post, who is writing a book on Casey and the CIA, and Seymour M. Hersh, who writes for The New York Times and whose book involves the downing of a Korean Air Lines jet by the Soviets in 1983.

He also called their publishers to deliver the same message, they said.

A spokesman for the CIA said that the agency "would not confirm or deny allegations about any of the director's private conversations."

Casey, who acknowledged to both publishers that he had not read their authors' manuscripts, has been on an open campaign in recent months to stop news organizations from publishing what he believes are intelligence leaks.

Casey, presidential national security affairs adviser John M. Poindexter and Gen. William E. Odom, director of the National Security Agency, have cautioned media organizations about the publication of sensitive material this year. Odom and Casey have threatened to seek prosecution. However, no legal action has been taken thus far.

In an interview in the July issue of the Washington Journalism Review, Casey said that revisions in espionage laws should be "carefully considered" because the statutes do not cover disclosures of secrets by the media. Foreign powers are able to "benefit greatly from sensitive, secret information they've been able to pick up in . . . the American media," Casey said.

In the past, Casey said, "we may not have done as good a job as we might have in sensitizing the media to the damage that is being done to our sources and methods. We're just now trying to do it in a more systematic and aggressive way."

He added later that although he felt an obligation to punish leakers in the government "when they hand out what might be said to be stolen goods, there is certainly some onus on the person receiving those goods. We should not close our eyes to that."

"We do not think the way to sensitize the press is to continue to threaten them with prosecution which, in effect, chills publication," said Jerry Berman, chief legislative counsel of the American Civil Liberties Union. "The media hype and the pressure and threat of prosecution is not an attempt to sensitize the press; it's an attempt to muzzle the press and abridge First Amendment rights.

"The idea of the head of the CIA cruising around making phone calls -- I hate to use a cliche such as a 'chilling effect' -- but it certainly does that," said Robert L. Bernstein, chairman of Random House which is publishing Hersh's book, "The Target Is Destroyed."

Bernstein, who said Casey called him yesterday to reaffirm earlier calls to Random House on the Hersh book, said that "nobody wants to publish classified material, that goes without saying." He said that Hersh had assured the publishers that they would not be publishing any classified material with his book.

"We don't think there are going to be any changes in the book," said Bernstein, who added that there are no plans to let Casey see it in advance.

"This method of calling like you were buddies and offering help doesn't ring true," Bernstein said. "It's disingenuous," he said, adding that it sounded much like the censorship used in Britain as part of the official secrets act.

"It's clearly a warning. I think you have to assume he was putting me on notice," Hersh said.

"I'm not interested in hurting national security, but I'm very aware of competing interests and that national security is often used to justify other things," Hersh said. He added later that he found Casey's recent efforts "an enormous intrusion on the process."

Woodward said that he took the call as a "friendly warning" from Casey.

"There was nothing blustery about it," he said. "My response was that I'm aware of his position and I take it into consideration but will feel my first allegiance is to write and publish what people need to know."

Woodward, whose book for Simon & Shuster does not yet have a title, said that he considered the call to be more in the nature of "negotiation, not intimidation."

"It's not clear territory, and I've talked to Casey about it," Woodward said. "I want to write what I want to write, but I don't want to have some sentence in there that doesn't add anything much but does cause harm. I look at it more as a dilemma."

Woodward, whose book is due out late this year or early next year, and Hersh, whose publication date is expected to be in August or September, said they had absolutely no plans to allow Casey to see their manuscripts in advance of publication.

Bernstein said that in Casey's call yesterday the CIA director said he was also planning to look at a book recently released by Viking Penguin Books on the Korean Air Lines disaster. The book, by British professor C.W. Johnson and entitled "Shootdown," argues that KAL Flight 007 was on a passive intelligence mission for the United States that would require the Soviets to activate their radar and allow the United States then to analyze the Soviet advances in this area.

Alan Kellock, president of Viking Penquin, said that he had not heard from Casey or anyone in government about the book.

Robert Loomis, who is Hersh's editor, said that the publishing house was also concerned about a call June 18 from a man who said his name was William Meyer of the National Security Agency. The man asked for a copy of the galley proofs of Hersh's book to determine whether the NSA should purchase copies.

A telephone call yesterday to the number the man had provided Random House was answered by a woman who said that there was no such person at that number. The woman did say that the telephone number was part of the National Security Agency.