NEW YORK » CBS ordered "60 Minutes" correspondent Lara Logan and her producer to take a leave of absence today following a critical internal review of their handling of the show’s October story on the Benghazi raid, based on a report on a supposed witness whose story can’t be verified.

The review, by CBS News executive Al Ortiz and obtained by The Associated Press, said the "60 Minutes" team should have done a better job vetting the story that featured a security contractor who said he was at the U.S. mission in Libya the night it was attacked last year.

Questions were quickly raised about whether the man was lying — something "60 Minutes" should have better checked out before airing the story, the report said.

The report also said Logan should not have done the story in the first place after making a speech in Chicago a year ago claiming that it was a lie that America’s military had tamed al-Qaida.

CBS News Chairman Jeff Fager, who is also the "60 Minutes" executive producer, said he had asked Logan and her producer, Max McClellan, to take a leave of absence of an undetermined length.

Fager said he prides himself on catching almost everything, "but this deception got through and it shouldn’t have." There was no word about whether Fager will face any repercussions for his role.

"The 60 Minutes" journalistic review is concluded, and we are implementing ongoing changes based on its results," said CBS News spokeswoman Sonya McNair, not making clear what those changes were.

The "60 Minutes" piece relied on testimony by Dylan Davies, a security official who was given a pseudonym in the report. The newsmagazine believed his account that he was at the scene even after informing CBS that he told his employers that he wasn’t there — something that Ortiz said should have raised a "red flag" about his story.

A few days later, The Washington Post said that Davies had filed a report with his employer, Blue Mountain, that he was at his villa on the night of the attack and not at the mission. CBS went back to Davies, who insisted he had been at the attack scene and had told that to the FBI, so Fager defended the "60 Minutes" story.

A week later, The New York Times reported that Davies had told the FBI that he was not on the scene. Within hours, CBS confirmed the Times story, which was later corroborated by a State Department source, and said that a correction would be issued.

Ortiz said the FBI report "was knowable before the (’60 Minutes’) piece aired." He said Logan and McLellan did not tap wider resources at CBS to try and track this information down. Ortiz mentioned no names, but CBS News reporter John Miller is a former law enforcement official with deep sources in the community.

Ortiz said that Logan’s claims that al-Qaida carried out the attack and controlled the hospital in Benghazi "were not adequately attributed in the report."

Logan’s Chicago speech in October 2012 before the city’s Better Government Association urged the U.S. to take action in response to Benghazi. Ortiz said it represents a conflict to take a public position on Benghazi and do the "60 Minutes" report.

Ortiz said CBS also erred in not acknowledging that Davies’ book telling his Benghazi story, which has been pulled from the shelves, was published by a fellow CBS Corp. company. In correcting the report, CBS had already made note of this oversight.

Ortiz’s report also said that questions have been raised about the authenticity of photos in the report, including one that displayed the schedule of the U.S. ambassador killed in the attack. Ortiz said those photos appear to be genuine.

"When faced with such an error, we must use it as an opportunity to make our broadcast even stronger," Fager wrote to his staff. "We are making adjustments at ’60 Minutes’ to reduce the chances of it happening again."

Congressional Republicans have insisted that the Obama administration misled Americans about the Benghazi attack, playing down a terrorist assault in the heat of the presidential campaign. Five GOP-led House committees have investigated, demanding documents and witnesses from the administration while complaining that the Obama team has been stonewalling.

A day after the CBS report, Sen. Lindsey Graham, R-S.C., said he would block President Barack Obama’s nominees for Federal Reserve chairman and Homeland Security chief until the administration allowed survivors of the assault on the U.S. diplomatic mission to talk to members of Congress.

The liberal advocacy group Media Matters for America had attacked CBS’ Benghazi report from the start. The group’s founder, David Brock, said he had urged appropriate action and "the network has done that. We hope this serves as a lesson learned to CBS about the danger of misinformation."