SAN FRANCISCO (AFP) - Billionaire Silicon Valley venture capitalist Tom Perkins was at the center of a social media firestorm on Monday for comparing protests against the rich to Nazi persecution of Jews.

Mr Perkins' publicly stated position even prompted the powerhouse investment firm bearing his name, Kleiner Perkins Caufield and Byers, to say he was not speaking on its behalf.

"Tom Perkins has not been involved in KPCB in years," the venture capital firm that Mr Perkins helped create said in a message fired off at Twitter, which was among its investments. "We were shocked by his views expressed today in the WSJ and do not agree."

Meanwhile, Mr Perkins on Monday was standing behind what he said in a letter published in the Wall Street Joural letter that ignited controversey over the weekend.

"Writing from the epicenter of progressive thought, San Francisco, I would call attention to the parallels of fascist Nazi Germany to its war on its 'one percent', namely its Jews, to the progressive war on the American one percent, namely the rich," Mr Perkins said in the opening of the letter. "This is a very dangerous drift in our American thinking," he wrote.

"Kristallnacht was unthinkable in 1930. Is its decendent 'progressive' radicalism unthinkable now?" Mr Perkins noted the Occupy movement and recent protests in San Francisco over buses provided by Google to shuttle tech workers to Silicon Valley.

Acivists in San Francisco have taken to blaming Internet company employees for driving up rents, housing prices and other aspects of living here.

"We have outrage over the rising real-estate prices which these 'techno geeks' can pay," Mr Perkins wrote.

Mr Perkins on Monday openly apologized for the 'Kritallnacht' reference but said that he still sees the demonization of the rich as a dangerous trend.

A Twitter post by @OccupyWallStNYC dismissed Mr Perkins assertion as "insane".