Former MSNBC anchor Keith Olbermann, who abruptly left his top-rated show at the U.S. cable news network last week, said on Monday that "reports of the death of my career are greatly exaggerated."

In his first comments since his departure, the liberal broadcaster, who often butted heads with MSNBC management, took to Twitter to share his thoughts with fans.

"My humble thanks to all Friends of Keith for the many kind words," he wrote on the social network, before paraphrasing a quote from Mark Twain. "The reports of the death of my career are greatly exaggerated."

It was not immediately clear how Olbermann planned to revive his career. He had two years left on his contract, when he signed off for the last time on his "Countdown with Keith Olbermann" political affairs program on Friday.

Neither Olbermann nor MSNBC gave a reason for the move, which came as Comcast Corp is finalizing a deal to acquire a 51 percent stake in MSNBC's NBC Universal parent from General Electric Co. A Comcast spokesman said his company had nothing to do with Olbermann's departure.

Olbermann left just over two months after he was briefly suspended by MSNBC for giving money to three Democratic politicians during the congressional election campaign, including U.S. Representative Gabrielle Giffords, who recently survived an assassination attempt in Arizona.

Olbermann's program helped define MSNBC as a liberal voice in cable television and a counterpoint to the conservative thrust of News Corp-owned Fox News, the ratings leader. MSNBC is now second in the ratings, ahead of Time Warner Inc's CNN.