One of America's top investigative journalists has been caught up in the government's probe into who leaked the identity of CIA officer, Valerie Plame.  Washington Post reporter Bob Woodward now says he was told by one of his sources the identity of the CIA officer some two years ago, but he withheld that information from his editors and federal investigators until recently.  The incident has again raised questions about journalistic practices in the United States.

As a reporter, book author, television analyst, and assistant managing editor of one of the most prestigious U.S. newspapers, Bob Woodward has long been a star of American journalism.  But it was his star status, say media analysts, that has landed Mr. Woodward in the middle of the controversy over the revelation of a CIA officer's identity.

Mr. Woodward revealed that a senior Bush Administration source had told him the identity of CIA covert officer Valerie Plame a month before it was publicly disclosed two years ago by a syndicated columnist.  Ms. Plame is married to former Ambassador Joseph Wilson, a leading critic of the Bush administration's rationale for going to war with Iraq.  Mr. Woodward made the disclosure in the Washington Post Wednesday, after testifying to a grand jury earlier this week. Mr. Woodward did not reveal the name of his source because, he says, the source has not authorized him to do so.

Vice-President Cheney's former chief of staff, Lewis Scooter Libby, has been indicted for perjury in connection with the leak investigation.  He has been identified as the source for other journalists on Ms. Plame's identity, but not as Mr. Woodward's.  It is unclear how the Woodward revelation will affect the case against Mr. Libby.

Mr. Woodward has appeared on television as an analyst discussing the Plame case, but never revealed his own involvement.  Nor, as it transpired, did he even disclose it to his own editors at the Washington Post, where he first won fame with colleague Carl Bernstein for reporting on the Watergate scandal in the 1970s.

Mr. Woodward never wrote a story about the Plame case.  But Bob Steele, who teaches journalistic ethics and values at the respected Poynter Institute, says Mr. Woodward should have at least told his boss, Washington Post executive editor Leonard Downie, of his knowledge when the story became important.

"To wait more than two years to tell Len Downie raises some significant questions about Bob Woodward's judgment in this case," said Mr. Steele.  "I respect Woodward's argument that he needed to protect a confidential source. But he should have at least had the conversation with his editor about having made that agreement with a source on a matter of such significant journalistic, ethical, and legal importance."

Mark Feldstein, director of the journalism program at George Washington University, says Mr. Woodward enjoyed a star status in which editors gave him much more independence and autonomy than other reporters.

"He probably, more than most reporters, has not had to bend quite as much to the editors who supervise him," said Mr. Feldstein.  "In fact, institutionally, he's more famous and probably more powerful within that organization than the editors who are his nominal superiors."

Journalists often use confidential sources, pledging never to reveal their identity.  Mr. Woodward and Mr. Bernstein kept the secret of their primary source in Watergate, nicknamed Deep Throat, for more than 30 years until released from their pledge.  Even their executive editor, Ben Bradlee, was not told the source's identity until after President Nixon resigned in 1974.  But Mr. Steele says editors need to know their reporters' sources to make sound judgments.

Mr. Steele adds that confidential sources are used far too much in American journalism.

"The use of confidential sources -- it's really a misuse and an overuse of confidential sources -- is a soft spot in the underbelly of at least American journalism," he said.  "Yes, we should keep that tool in the bag and use it on occasion, because it may be essential in stories in which we're doing heavy-duty investigation and stories in which we need to legitimately protect a whistle-blower.  But we too quickly and easily give confidentially to certain sources.  And way too often we're giving protection to sources who are making personal attacks against someone."

Another Washington Post reporter, Walter Pincus, was cited for contempt of court Wednesday for failing to reveal who gave him privileged information about the investigation of nuclear scientist Wen Ho Lee.  Federal investigators had suspected Mr. Lee of passing weapons-design secrets to China, and the charges were widely reported in the media.  All but one of the charges were dropped for lack of evidence.  Mr. Lee is suing the government for violating U.S. laws governing personal privacy.