(Adds NBC saying alleged misconduct began at 2014 Sochi winter Olympics, reported comment from accuser's lawyer, detail on 'Today' advertising revenue, Viacom CEO comment)
NEW YORK, Nov 29 (Reuters) - NBC News fired popular "Today" show host Matt Lauer after receiving what it called a detailed complaint from a colleague about inappropriate sexual behavior in the workplace, the network said on Wednesday.
NBC News chairman Andrew Lack said that, after serious review, the complaint received on Monday night represented "a clear violation" of the company's standards.
"As a result, we've decided to terminate his employment," Lack said in a statement. "While it is the first complaint about his behavior in the over twenty years he's been at NBC News, we were also presented with reason to believe this may not have been an isolated incident."
Lauer's agent Ken Lindner did not respond to a request for comment.
The news was announced by "Today" co-anchors Savannah Guthrie and Hoda Kotb at the start of the talk show, a staple of U.S. morning television for more than six decades that, NBC says, averages more than 4 million viewers.
"We just learned this moments ago just this morning," Guthrie said, visibly shaken. "As I'm sure you can imagine we are devastated."
Lack's statement did not say who made the accusation. Lauer, 59, is married.
"We are deeply saddened by this turn of events," the statement said. "But we will face it together as a news organization - and do it in as transparent a manner as we can."
The New York Times quoted Ari Wilkenfeld, a civil rights lawyer with the firm Wilkenfeld, Herendeen & Atkinson in Washington, who said he represented the woman who made the complaint to NBC but declined to publicly identify her.
My client and I met with representatives from NBCs Human Resources and Legal Departments at 6 p.m. on Monday for an interview that lasted several hours. Our impression at this point is that NBC acted quickly, as all companies should, when confronted with credible allegations of sexual misconduct in the workplace," Wilkenfeld said in a story published by the Times on Wednesday.
The law firm representing Lauer's accuser did not immediately respond to a request for comment.
The complaint said the sexual misconduct occurred while Lauer and the female colleague were covering the 2014 Sochi winter Olympics in Russia, NBC News reporter Stephanie Gosk said on-air.
The misconduct continued after the Games, Gosk said. An NBC representative did not respond to a request for more details.
Fellow NBC News anchor Willie Geist, who hosts the "Today" show's Sunday program, told MSNBC's "Morning Joe" that he was stunned, especially given Lauer's role.
"Matt Lauer is the most powerful person at NBC News, arguably," Geist said, referring to Lauer as a friend and mentor who he said had always led by example on the show's set.
Comcast Corp, the largest U.S. cable television company, owns NBCUniversal. Shares of Comcast rose 3.4 percent to $37.49 in morning trade on Nasdaq.
U.S. President Donald Trump responded with messages on Twitter calling for some of Lauer's colleagues to be fired too, and adding to his recent attacks against multiple U.S. news outlets for their reporting on his administration.
"Wow," Trump wrote about the Lauer announcement. "But when will the top executives at NBC & Comcast be fired for putting out so much Fake News. Check out Andy Lack's past!" he added, without further explanation.
An NBC spokeswoman did not respond to questions about Trump's comments.
During the 2016 presidential campaign, then-Republican candidate Trump was accused by 13 women who publicly said that in the past he had physically touched them inappropriately in some way, the Washington Post reported.
Trump denied the accusations, accused rival Democrats and the media of a smear campaign, and went on to win the election.
Just last week, Lauer co-hosted with Guthrie NBC's Thanksgiving Day coverage of the Macy's parade in Manhattan.
Since Lauer took over the anchor chair in 1997, "Today" has dominated morning show ratings. It earned $509 million in advertising revenue last year, more than any other morning show, New York-based analysts Kantar Media said.
Lauer signed a two-year deal in 2016 that would pay him $20 million per year, according to Fortune Magazine. He joined "Today" in January 1994 and has interviewed presidents George Bush and Barack Obama and broadcast from seven Olympic games.
There were reports that journalists from multiple outlets had been investigating complaints against Lauer.
Elizabeth Wagmeister and Ramin Setoodeh, two Variety reporters, said they had been working for months on a story about sexual harassment allegations by multiple women against Lauer. "NBC was aware that Variety was working on a bombshell story about sexual harassment allegations against Matt Lauer," Setoodeh wrote on Twitter.
This is not a Hollywood media problem, this is a problem across all industries including the U.S. government, said Bob Bakish, CEO of Viacom Inc, when asked about the Matt Lauer firing, at the Business Insider IGNITION Conference in New York on Wednesday. Secondly, this is not a U.S. problem, it is a global problem.
(Reporting by Gina Cherelus and Jonathan Allen; Additional reporting by Susan Heavey in Washington, Jessica Toonkel in New York and Supantha Mukherjee in Bengaluru; Editing by Alden Bentley, Howard Goller and Nick Zieminski)