"So Obama has thrown in his lot with Silicon Valley paymasters who threaten all software creators with piracy, plain thievery," News Corp's chairman and chief executive officer posted on his personal Twitter account Saturday.

Murdoch, whose media empire includes Fox TV, The Wall Street Journal, Fox Studios and the Sun newspaper in Britain, continued with several tweets, attacking Google as the "Piracy leader" for streaming movies free. In later tweets he called Google a "great company."

Google could not be reached for an immediate comment. The White House declined to make any other comment beyond their statement issued Saturday.

At issue are the concerns White House officials raised on Saturday about elements in the proposed Stop Online Piracy Act (SOPA) pending in Congress.

Google and Facebook already have decried as heavy-handed and Hollywood studios and music labels say is needed to save U.S. jobs.

In a blog posting, three advisers to President Barack Obama said they believed the act and similar bills could make businesses on the Internet vulnerable to litigation and harm legal activity and free speech.

"Any effort to combat online piracy must guard against the risk of online censorship of lawful activity and must not inhibit innovation by our dynamic businesses large and small," said the officials, including White House cyber-security czar Howard Schmidt.

The House of Representatives' SOPA bill aims to crack down on online sales of pirated American movies, music or other goods by forcing Internet companies to block access to foreign sites offering material that violates U.S. copyright laws.

U.S. advertising networks could also be required to stop online ads and search engines would be barred from directly linking to websites found to be distributing pirated goods.

Those who support stricter piracy rules reacted strongly to Saturday's White House statement, which darkened prospects for legislation already expected to struggle to clear Congress in an election year.

Schmidt and the other advisers said the Obama administration was ready to work with lawmakers on a narrower, more targeted approach to online piracy to ensure that legitimate businesses -- including start-up companies -- would not be harmed.

Murdoch, who opened his Twitter account this year, has used it to colorfully opine on a number of topics. Tweeting last week, Murdoch praised New York City Mayor Michael Bloomberg's latest proposal to overhaul the city's public schools, but referred to New York State Governor Andrew Cuomo as "chicken Cuomo."

He also admitted in a post to his company's mishandling of social network MySpace, which News Corp bought in 2005 for $580 million. Today the site is nearly irrelevant.

"...we screwed up in every way possible.." Murdoch posted last week.

(Reporting By Ilaina Jonas, editing by Maureen Bavdek)

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