In another installment of the cat-and-mouse game that the affair of the CIA spy's leaked name has become, conservative columnist Robert Novak gave an unexpected glimpse yesterday at his role in the matter, something he promised he would not do until it was all over.

Novak, widely criticized for his largely silent posture -- even as another reporter went to jail to protect a source in the case -- broke his silence yesterday in his Chicago Sun-Times column to defend himself against allegations that he had "deliberately disregarded" advice not to reveal the identity or activities of CIA agent Valerie Plame.

The question of Novak's motives, and those of Bush administration officials who may have divulged Plame's name in order to retaliate against her husband, a Bush critic, is central to a case that has ensnared Karl Rove, the president's senior political adviser, in its tentacles.

Bristling with defensiveness, Novak described as "just plain wrong" a statement last week by a former CIA spokesman, Bill Harlow, that he had told Novak two years ago to hold off on revealing Plame's name in a column about her husband, former U.S. Ambassador Joseph C. Wilson IV, who had gone to Niger at the CIA's request to investigate reports that Saddam Hussein had tried to buy enriched uranium there.

Wilson concluded there was no evidence of any such purchase. Nevertheless, President Bush, citing British government sources that later proved false, said in his 2003 State of the Union address that the purchase was real, and cited it as a reason to invade Iraq. Wilson, in a July 6, 2003, op-ed piece in The New York Times, posed the question, "Did the Bush administration manipulate intelligence about Saddam Hussein's weapons programs to justify an invasion?"

The outing of Wilson's wife included assertions that Wilson had not received top-level clearance for his trip to Niger, instead relying on his wife's intercession for authority to go there.

In a Washington Post article last week, Harlow was quoted as saying that he had warned Novak, "in the strongest terms he was permitted to use without revealing classified information," that Wilson's wife had not authorized the mission and that if he wrote about the matter her name should not be revealed.

Harlow said he had ascertained that Plame was an undercover operative, but did not share that information with Novak because it was classified.

Novak is not letting Harlow's comments go unchallenged.

"Though frustrated, I have followed the advice of my attorneys and written almost nothing about the CIA leak over two years because of a criminal investigation by a federal special prosecutor," Novak wrote in his column. "The lawyers also urged me not to write this."

But he felt compelled to reply, he said, because "the allegation against me is so patently incorrect and so abuses my integrity as a journalist."

Novak -- the first journalist to publish Plame's name, on July 14, 2003 -- delved into the question of whether she had authorized or merely suggested that her husband travel to Niger, and took issue with Harlow's memory of their conversations.

"He told the Post reporters he had 'warned' me that if I 'did write about it her name should not be revealed,'" Novak wrote. "That is meaningless. Once it was determined that Wilson's wife suggested the mission, she could be identified as 'Valerie Plame' by reading her husband's entry in Who's Who in America."

Yet in a column published Oct. 1, 2003, Novak wrote that the CIA official with whom he spoke, presumably Harlow, "asked me not to use her name, saying she probably never again will be given a foreign assignment," and that "exposure of her name might cause 'difficulties' if she travels abroad.

"He never suggested to me that Wilson's wife or anybody else would be endangered," Novak wrote at the time. "If he had, I would not have used her name."

In his latest column, Novak, who did not respond yesterday to a request for an interview, objected to the notion that he had "ignored an official's statement that I had the facts wrong but wrote it anyway for the sake of publishing the story. That would be inexcusable for any journalist and particularly a veteran of 48 years in Washington," he wrote.

He also expressed antipathy toward Wilson, saying the former diplomat had been "discarded a year ago by the Kerry presidential campaign" after a Senate committee concluded that much of what he said about the Niger issue "had no basis in fact."

But Novak's decision to address only partially the issue of his involvement, after many months of unanswered questions about it, did not sit well with some fellow journalists.

"It's sort of frustrating," said Michael Hoyt, executive editor of Columbia Journalism Review. "It's like the prairie dog who sticks his head up and goes back down again into the dark, where you can't ask him any more questions."

In Novak's column yesterday, Hoyt said, "he defends himself, but whether he's defending himself by splitting hairs is another question."

Hoyt, referring to Novak's parting shot at Wilson, said Novak ought not be able to fire such barbs without engaging in a debate about the case, which resulted in the jailing of Judith Miller of the Times for contempt of court and near-jailing of Matthew Cooper of Time magazine.

"We don't know what constraints Novak has," Hoyt said, "but Matt Cooper was able to talk about it after he appeared before the grand jury."

Gary Hill, chairman of the ethics committee of the Society of Professional Journalists, said the entire case was "fraught with unanswered questions."

"Most journalists support Judy Miller's path," said Hill, news manager for special projects at KSTP-TV in Minneapolis-St. Paul. "But what about Novak? What has he done and how has he escaped the pressure? ... Is he not talking or is he just talking at the moment? He appears to be having it both ways. He's defending himself in this particular instance while at the same time not telling us everything he knows."