NEW YORK - Brian Williams will not return as anchor of the "NBC Nightly News," but will take on a new role at MSNBC as anchor of breaking news and special reports, the network announced Thursday.

Lester Holt, the network veteran who stepped behind the anchor desk on an interim basis, will officially take over. A highly regarded figure inside 30 Rock, Holt has kept the ratings race competitive against ABC's "World News Tonight."

Holt said the promotion is "an enormous honor" and praised the "NBC Nightly News" team for producing "world-class journalism" the past several months under the media spotlight. "Im very proud and grateful to be part of such an unflappable and dedicated team of professionals as we move forward together."

Andy Lack, a former NBC News president who returned in March to steady the ship, said Holt "has done outstanding work for NBC News over the last 10 years, and hes performed remarkably well over the last few months under very tough circumstances."

The announcement caps four months of speculation over whether Williams would resume anchor duties after being suspended in February for exaggerating an account of his Iraq war reporting in public appearances. During that time, NBC News' investigative unit has conducted an internal review examining Williams' reporting and commentary over the past decade, both on the network's broadcast and in public settings.

"The extensive review found that Williams made a number of inaccurate statements about his own role and experiences covering events in the field," the network statement read. "The statements in question did not for the most part occur on NBC News platforms or in the immediate aftermath of the news events, but rather on late-night programs and during public appearances, usually years after the news events in question."

A NBC News spokesman declined to comment as to whether the network will release the findings of its internal review.

"Im sorry. I said things that werent true," William said in a statement. "I let down my NBC colleagues and our viewers, and Im determined to earn back their trust. I will greatly miss working with the team on Nightly News, but I know the broadcast will be in excellent hands with Lester Holt as anchor. I will support him 100% as he has always supported me."

"I am grateful for the chance to return to covering the news," Williams continued. "My new role will allow me to focus on important issues and events in our country and around the world, and I look forward to it.

Williams, who will appear Friday on the "Today" show, did not specify what "things" were untrue, and the network didn't specify in its release which were the "inaccurate statements." The decision by NBC News not to release its findings demonstrates a lack of transparency, which news organizations routinely criticize in government or the corporate world.

There have been questions raised about accounts Williams has given of reporting on Hurricane Katrina , the Israel-Hezbollah War and the fall of the Berlin Wall .

In February, the Huffington Post examined Willliams' claims about interaction with members of SEAL Team 6, the elite force that killed Osama Bin Laden. Williams claimed to have embedded with SEAL Team 6 during a flight into Baghdad, though a government spokesman said that elite unit doesnt allow journalist embeds. He also claimed to have received a piece of the fuselage from the helicopter that crashed at bin Ladens compound from a member of SEAL Team 6. Williams may have a piece, though it was reportedly sent from a colleague at NBC News in an unmarked envelope.

In April, The Washington Post reported the network discovered 11 embellishments in Williams' reporting.

Within MSNBC, theres concern that managements move may create a misperception that journalistic standards are lower at the cable news network. If Williams isn't credible enough to anchor the broadcast news, as the decision may be interpreted, is he credible enough to anchor breaking news on cable?

But the move makes sense from a network standpoint in that Williams signed a five-year, $50 million contract, and firing him would result in a large payout. In addition, Lack has already been expected to make significant programming changes at MSNBC given the networks ratings plunge. Bringing in Williams, however tarnished, still adds star wattage to a struggling operation. He was also an MSNBC anchor from 1996 to 2004, while being groomed to take over the "Nightly News."

Steve Burke, chief executive of NBCUniversal, said that with Williams' move to MSNBC, he "now has the chance to earn back everyones trust" and that "his excellent work over twenty-two years at NBC News has earned him that opportunity.

Burke also indicated the network won't publicly reveal what was discovered in its investigation. "This matter has been extensively analyzed and deliberated on by NBC," he said. "We are moving forward.