"NBC Nightly News" anchor Brian Williams could face new questions this week over differing versions of a story he repeatedly told about coming under Hezbollah rocket fire while riding in an Israeli Defense Forces helicopter in 2006, according to a published report.

The Washington Post reported late Sunday that Williams has given differing accounts of how close the rockets came to the helicopter he was riding in over northern Israel.

In a blog post written for NBCNews.com and dated July 18, 2006, Williams said that he was flying "at 1,500 feet" in a Blackhawk helicopter with a high-ranking Israeli general while rockets were being launched by the terror group into northern Israel from southern Lebanon. In the blog, Williams says the helicopter pilot tells him the rockets "landed about 30 seconds ago." At that point, Williams says, he witnesses a rocket launch, about six miles away.

"A rising trail of smoke, then a second rocket launch, an orange flash and more smoke — as a rocket heads off toward Israel," Williams says.

However, a month later, Williams made an appearance on Comedy Central's "The Daily Show", and told host Jon Stewart about "a view of rockets I have never seen, passing underneath us, 1,500 feet beneath us." There is no such description of the rockets passing underneath the helicopter in Williams' original blog post.

The anchor continued, "And we’ve got the gunner doors [open] on this thing, and I’m saying to the general, some four-star: ‘It wouldn’t take much for them to adjust the aim and try to do a ring toss right through our open doors, would it?’ ”

Williams repeated the later version story to a student interviewer at Fairfield University in Connecticut in November 2007.

In that interview, Williams says the rockets passed "just beneath the helicopter I was riding in."

Williams, who has anchored NBC's flagship newscast since 2004, announced late Saturday that he was stepping away from "Nightly News" for "the next several days" following revelations he made false statements about his experience reporting in Iraq in 2003.

Earlier this week, the military newspaper "Stars and Stripes" published a story, based on eyewitness accounts of the incident, saying Williams was incorrect when he said a helicopter in which he and his team were traveling during the invasion of Iraq was hit by rocket propelled grenades.

Williams apologized on air Wednesday, but the firestorm surround the incident has continued, including calls for his resignation.

Questions have also been raised about his claim that he saw a body or bodies in the Hurricane Katrina floodwaters that hit New Orleans.

NBC News President Deborah Turness said in an internal memo Friday that the network has assigned the head of its own investigative unit to look into Williams' statements.

The Associated Press contributed to this report.

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