Keith Olbermann, the liberal, outspoken anchor of MSNBC's Countdown show, had his contract dramatically terminated by the US cable news network's parent company NBC on Friday night.

Olbermann had two years of a four year contract remaining, worth an estimated $30m, and was the network's highest-rated personality, responsible in large part for MSNBC's orientation as a liberal, Democratic-leaning channel.

Abruptly announcing in a lengthy farewell that the current show would be his last, Olbermann said: "This may be the only television programme wherein the host was much more in awe of the audience than vice versa. You will always be in my heart for that."

Giving no reason for the departure, Olbermann ended by calmly reading aloud a piece by James Thurber before signing off with the words: "Good night and good luck."

While Olbermann was live on-air, NBC issued a statement reading:

Statement regarding Keith Olbermann MSNBC and Keith Olbermann have ended their contract. The last broadcast of Countdown with Keith Olbermann will be this evening. MSNBC thanks Keith for his integral role in MSNBC's success and we wish him well in his future endeavors.

The Associated Press reported that Phil Griffin, MSNBC's president, would not comment on Olbermann's sudden departure. But a spokesman did say that the acquistion of NBC Universal by cable and telecoms giant Comcast, which received regulatory approval this week, had nothing to do with the decision.



As speculation swirled about the timing, Comcast later put out a statement denying any connection:

"Comcast has not closed the transaction for [NBC-Universal] and has no operational control at any of its properties including MSNBC. We pledged from the day the deal was announced that we would not interfere with NBCU's news operations. We have not and we will not."

Olbermann had a stormy relationship with management and had been suspended from hosting the nightly show by the network last November after violating station rules by making donations to three Democratic candidates. He was reinstated the following week. (One of the three candidates was Gabrielle Giffords, the Arizona congresswomen attacked in Tucson.)

Olbermann's show Countdown, which screened at 8pm and repeated at 11pm, was the network's top-rated programme. On Thursday the show attracted 1.1 million viewers, according to Nielsen ratings, far ahead of CNN's Parker-Spitzer, which managed just 520,000 in the same time slot. Fox News's Bill O'Reilly – a frequent target of Olbermann's ire – dominated the hour with 2.9 million viewers.

Olbermann's departure leaves Rachel Maddow as the network's biggest name. Appearing on the Bill Maher show on HBO last night, Maddow said: "All I know is that it was between Keith and the company."

MSNBC later announced that Lawrence O'Donnell, host of the channel's 10pm output, will take over the 8pm slot, with Ed Schultz's show moving from 6pm to 10pm.

Media commentator Dan Kennedy summed up Olbermann's value to MSNBC:

MSNBC executives tonight should be thanking their stars that Olbermann came along when he did. It was he who led the way toward transforming the operation into a liberal alternative to Fox News — a profitable network that, though still far behind Fox, kicks CNN's tail in the ratings.

Piers Morgan, finishing his first week as host of CNN's 9pm interview slot, tweeted: