ABC's Jonathan Karl is drawing criticism from journalism veterans and media ethicists who say his recent reporting on talking points related to the September attacks on diplomatic facilities in Benghazi, Libya has been “sloppy” and “highly problematic ethically.”

The conservative media and Republican politicians have claimed for months that the Obama administration had for political purposes edited references to terrorism out of a set of talking points used shortly after the attacks.

On May 10, Karl gave those claims new life with an “exclusive” online report that found, based on what appeared to be direct quotes from the emails of White House and State Department aides, that “the edits were made with extensive input from the State Department.”

Karl's muddled account reported both that “White House emails reviewed by ABC News” and that “summaries of White House and State Department emails” led to that conclusion. He also repeatedly produced quotes from what he described as “emails,” suggesting that he had personally reviewed the original documents. In on-air reports, Karl and his colleagues subsequently claimed he had “obtained” the emails.

But after CNN produced the full text of one of the emails Karl had cited and reported that the version in Karl's article had made it “appear that the White House was more interested in the State Department's desire to remove mentions of specific terrorist groups and warnings about these groups so as to not bring criticism to the State Department” than was actually the case, Karl acknowledged that he had actually been “quoting verbatim” an unnamed source “who reviewed the original documents and shared detailed notes,” and had not seen the emails himself. Observers have suggested that Karl had been burned by his source, given the discrepancies between what Karl reported about the email and what it actually said in full.

The slippery language Karl and ABC News adopted in describing the emails has drawn fire from media ethicists and veteran journalists.

“At best, it's extremely sloppy. At worst, it's a deliberate attempt to conceal the secondhand -- and possibly distorted -- nature of the information ABC was relying on so as to put its shoulder to the wheel of a highly prejudicial reading of the affair,” said Edward Wasserman, dean of the Graduate School of Journalism at the University of California, Berkeley, and a Miami Herald columnist. "Whether best or worst is true, it's highly problematic ethically, and the failure to acknowledge and correct is even worse."

Tim McGuire, journalism professor at Arizona State University and former president of the American Society of News Editors, criticized Karl for failing to adhere to basic standards of ethics.

“If the ethical journalist is dedicated to transparency Mr. Karl seems to have failed that standard,” he said in an email. “The Benghazi story raises such trust issues anyway it seems to me all the details of what Mr. Karl saw are crucial to both sides.”

Tom Fiedler, dean of the Boston University College of Communication and former Miami Herald executive editor, said Karl's report “cries out for a correction.”

“Karl was sloppy - or being deliberately ambiguous - about these e-mails to enhance the 'exclusive' he claimed to have,” Fiedler said. “Most important here is whether the 'summaries' of the e-mails cast a different light on the event than the e-mails themselves.”

Fiedler said that Karl's reporting has suffered from its inconsistent and at times false descriptions of what he had reviewed.

“At minimum, Karl should have acknowledged on the air and in his on-line postings that he had only seen (or had read to him) summaries, and that he couldn't say whether those summaries were in context of the original e-mails,” he added. “This caveat is no small thing as Karl could well have left himself vulnerable to being used for political purposes.”

Kevin Smith, chair of the Society of Professional Journalists' ethics committee, called it “inaccurate reporting.”

“I don't understand how you can claim to have the emails but then backtrack and say you were quoting from summaries,” he said. “What was the fact when you initially reported - had the emails or summaries? Were you trumping up the story? Did you know the difference and if you did, why did you misrepresent? In the end I'd say there is a serious credibility issue with ABC's reporting on this issue.”

Alicia Shepard, a former NPR ombudsman, called out ABC News, saying they were “wrong to mischaracterize information as a direct quote from an email when it was a summary.”