WASHINGTON — President Bush's chief spokesman said yesterday that the allegation that administration officials leaked the name of a CIA operative is "a very serious matter" and vowed that Bush would fire anybody responsible for such actions.

The vow came as numerous Democratic leaders demanded the administration appoint a special counsel to investigate the allegations that a CIA operative's name was divulged in an effort to discredit her husband, a prominent critic of Bush's Iraq policy. The White House rejected those demands, saying it has no evidence of wrongdoing by Bush adviser Karl Rove or others and therefore has no reason to begin an internal investigation.

"There's been nothing, absolutely nothing, brought to our attention to suggest any White House involvement... " said Scott McClellan, Bush's press secretary. He said that "if anyone in this administration was involved in it, they would no longer be in this administration."

Justice Department officials said yesterday they have begun a preliminary probe into whether an administration official violated the law by telling journalists that the wife of former Ambassador Joseph Wilson IV worked for the CIA. Wilson has drawn attention for his report of a trip he took to Niger for the CIA that, he said, did not confirm an administration claim that Iraq was seeking nuclear material in that country.

A senior official quoted Bush as saying, "I want to get to the bottom of this," during a meeting yesterday morning with a few top aides, including Rove.

Senior intelligence officials said yesterday that the CIA filed what they termed a "crime report" with the Justice Department in late July, shortly after syndicated columnist Robert Novak, citing two unnamed administration sources, identified Wilson's wife by name. The CIA report pointed to a "possible violation of federal criminal law involving the unauthorized disclosure of classified information."

Three weeks ago, intelligence officials said, the CIA returned to the Justice Department a standard 11-question form detailing the potential damage done by the release of the information. Word of the Justice probe emerged over the weekend after the CIA briefed lawmakers on it last week.

Another journalist yesterday confirmed receiving a call from an administration official providing the same information about Wilson's wife before the Novak column appeared July 14. The journalist, who asked not to be identified because of possible legal ramifications, said that the information was provided as part of an effort to discredit Wilson, but that the CIA information was not treated as especially sensitive.

"The official I spoke with thought this was a part of Wilson's story that wasn't known and cast doubt on his whole mission," the person said, declining to identify the official with whom he spoke.

In addition to Novak's column, an administration official told The Washington Post on Saturday that two White House officials leaked the information to several journalists in an effort to discredit Wilson.

An article that appeared on the Time magazine Web site the same day Novak's column was published said that "some government officials have noted to Time in interviews ... that Wilson's wife, Valerie Plame, is a CIA official who monitors the proliferation of weapons of mass destruction." The same article quoted from an "exclusive interview" with I. Lewis Libby, Vice President Dick Cheney's chief of staff, saying that Cheney did not know about Wilson's mission "until this year when it became public in the last month or so."

Neither the Novak nor the Time account mentioned that Plame had worked as an undercover operative, which indicates that those who leaked the information may not have known she was. Novak, co-host of CNN's "Crossfire," said on the program yesterday that he was not called with the leak but got the information during interviews.

The CIA "asked me not to use her name but never indicated it would endanger her or anybody else," Novak said. "According to a confidential source at the CIA, Mrs. Wilson was an analyst, not a spy, not a covert operative, and not in charge of undercover operatives."

Sources said Wilson's wife is a clandestine operations officer for the CIA, currently out of the field and working on weapons of mass destruction.

At a forum held last month by Rep. Jay Inslee, D-Wash., Wilson said: "I don't think we're going to let this drop. At the end of the day it's of keen interest to me to see whether or not we can get Karl Rove frogmarched out of the White House in handcuffs. And trust me when I use that name. I measure my words."

Wilson said yesterday that he believes Rove "at a minimum condoned the leak" but said he has no direct evidence Rove originated the leak. Wilson said that based on statements reporters made to him, he believes Rove participated in calls that drew attention to his wife's occupation after Novak's column ran. "My knowledge is based on a reporter who called me right after he had spoken to Rove and said that Rove had said my wife was fair game," Wilson said. He said that conversation occurred July 21.

Wilson said a producer from another network told him about the same time, "The White House is saying things about you and your wife that are so off the wall that we won't use them." Wilson said the series of similar calls he received, which included four journalists from three networks, stopped on July 22, after he appeared on NBC's "Today" show and said the disclosure of his wife's maiden name could jeopardize the "entire network that she may have established."

McClellan said Rove "wasn't involved" in any disclosure of the operative's name. "The president knows he wasn't involved. ... It's simply not true."

Justice Department officials said yesterday they have opened a preliminary inquiry to determine whether to investigate a possible violation of the law protecting the identities of undercover intelligence operatives.

If they decide grounds exist for a full-blown investigation, Attorney General John Ashcroft would have to decide whether he should name a special counsel to oversee the case. Among the considerations that could lead to the naming of a special counsel are the inherent conflict of interest in having the Bush Justice Department investigate employees of the Bush White House, department officials said.