The New York Times acknowledged today that its coverage of whether Saddam Hussein had weapons of mass destruction "was not as rigorous as it should have been" and that "we wish we had been more aggressive in re-examining the claims as new evidence emerged -- or failed to emerge."

More than a year after Judith Miller and some Times colleagues reported on evidence suggesting that Iraq was hiding such weapons, the paper said in an editors' note: "Editors at several levels who should have been challenging reporters and pressing for more skepticism were perhaps too intent on rushing scoops into the paper. Accounts of Iraqi defectors were not always weighed against their strong desire to have Saddam Hussein ousted. Articles based on dire claims about Iraq tended to get prominent display, while follow-up articles that called the original ones into question were sometimes buried. In some cases, there was no follow-up at all."

One of Miller's prime sources was Ahmed Chalabi, the Iraqi exile whose organization was subsidized by the Pentagon and who "has provided most of the front page exclusives on WMD to our paper," according to an e-mail she sent to a colleague. U.S.-backed forces raided Chalabi's home in Iraq last week amid allegations that members of his Iraqi National Congress may have been providing sensitive information to Iran.

Dan Okrent, the paper's ombudsman, said last night that "I'm looking into the coverage of WMD" and planned to publish his findings Sunday. Executive Editor Bill Keller said last night he was busy on deadline and could not discuss the situation.

The editors' note did say that "we found an enormous amount of journalism that we are proud of. In most cases, what we reported was an accurate reflection of the state of our knowledge at the time, much of it painstakingly extracted from intelligence agencies that were themselves dependent on sketchy information."

While many news organizations reported on WMD claims before the war, few did so as aggressively as the Times. The failure to find such weapons has produced growing calls by critics, led by Slate columnist Jack Shafer, for the Times to own up to past errors.

Miller played an unusually active role while embedded last year with an Army unit searching for weapons of mass destruction, at one point writing to object to a commander's order that the unit withdraw from the field and suggesting she would write about it unfavorably in the Times. The pullback order was later rescinded. The unit "is using Chalabi's intell and document network for its own WMD work," Miller wrote her colleague.

Some of the Times's earlier reporting "depended at least in part on information from a circle of Iraqi informants, defectors and exiles bent on 'regime change' in Iraq, people whose credibility has come under increasing public debate in recent weeks," the editors said.

Among the problematic stories cited:

* In October and November 2001, front-page pieces cited Iraqi defectors who described a secret camp where terrorists were trained and biological weapons produced. "These accounts have never been independently verified."

* In December 2001, Miller cited an Iraqi defector who said he had worked on renovations of secret facilities for biological, chemical and nuclear weapons. While weapons might still be found, "in this case it looks as if we, along with the administration, were taken in. And until now we have not reported that to our readers."

* A lead article in September 2002, co-authored by Miller, was headlined "U.S. Says Hussein Intensified Quest for A-Bomb Parts." The story "should have been presented more cautiously," and "misgivings" that surfaced days later "appeared deep in an article on Page A13, under a headline that gave no inkling that we were revising our earlier view."

* In April 2003, Miller reported that an Iraqi scientist who claimed to have worked in the country's weapons program "has told an American military team that Iraq destroyed chemical weapons and biological warfare equipment only days before the war began," and that the team had found "precursors" of banned toxic agents. But "The Times never followed up on the veracity of this source or the attempts to verify his claims." Miller had said on PBS that the scientist was not just a "smoking gun" but "a silver bullet."

In a New York Review of Books interview, Miller said her note about Chalabi was exaggerated as part of "an angry e-mail exchange" with colleague John Burns.

In a note to Okrent in March, Keller said he "did not see a prima facie case for recanting or repudiating the stories." He called Miller "a smart, well-sourced, industrious and fearless reporter with a keen instinct for news, and an appetite for dauntingly hard subjects."

Judith Miller reported on the search for weapons of mass destruction in Iraq.N.Y. Times Executive Editor Bill Keller.