By Erik Kirschbaum

BERLIN (Reuters) - German actor and singer Manfred Krug, one of the few performers to find fame on both sides of his divided country during the Cold War, has died in Berlin aged 79, his management company said.

Communist authorities banned him from performing in East Germany in 1977 after he expressed support for a dissident folk singer and he asked to leave soon after.

In West Germany, his career picked up again, as he released songs, published books and starred in television series.

Krug became the public face for Deutsche Telekom's gigantic initial public offering in 1996 - only to burn his bridges with his corporate sponsors later by publicly apologizing to shareholders who lost money.

"His greatest accomplishment was that he was first a star in East Germany and then became a star in all of Germany," said Berlin Mayor Michael Mueller. "Krug was never afraid to stand up for what he believed in."

Krug was born in Duisburg, West Germany in 1937 and moved to Communist East Germany with his father, an engineer in the steel industry, in 1949.

He started acting in 1957 and came up against the authorities less than a decade later, appearing in the East German film "Spur der Steine" (Trace of Stones) that was branded anti-Socialist soon after its release and banned.

Another decade on, he signed a petition against the expulsion of folk singer Wolf Biermann, then headed west.

He died on Oct. 21, but his family had wanted a private funeral before going public, his managers K&V Events said.

"I'll remember Manfred Krug as one of the most authentic and popular actors of our age," the country's president Joachim Gauck, another East German, said on Thursday.

"Whether on television, in films or on the stage, he showed us the strengths and weaknesses of human beings with his wonderful style."

(Reporting by Erik Kirschbaum; Editing by Andrew Heavens)