News Corp chief accuses White House of siding with 'Silicon Valley paymasters' as two bills go through US Congress

The gathering storm over online piracy legislation being debated in the US Congress has sucked two more heavy hitters into the fray, with the Obama administration and Rupert Murdoch lining up on opposite sides of the argument.

The controversy over the Stop Online Piracy Act (Sopa) going through the House of Representatives and its Senate equivalent, the Protect Intellectual Property Act (Pipa), has intensified. Websites including Reddit and possibly Wikipedia are planning to "go dark" on Wednesday in protest at the proposals, which they say will lead to government censorship of the internet and be disastrous for innovation.

On Saturday, the Obama administration made clear that it would not tolerate several of the more controversial aspects of the two bills, particularly the power to interfere with the architecture of the web by tampering with its Domain Name System (DNS).

"We will not support legislation that reduces freedom of expression, increases cybersecurity risk, or undermines the dynamic, innovative global internet," said three of Obama's top technology advisers in a statement. The authors said manipulating the DNS by forcing service providers to block access to pirating sites could damage cybersecurity by driving users to much more unscrupulous servers.

Just before the White House statement was issued, a sponsor of Sopa – the Texan congressman Lamar Smith – said the DNS blocking provision in the bill would be dropped.

Under the two bills, the US department of justice would have the power to censor foreign websites engaging in piracy by requiring search engines, payment portals and online advertising networks to desist from carrying them.

Murdoch – whose News Corporation includes the Hollywood studio 20th Century Fox, which is among the companies calling for a legislative clampdown against piracy of films, music and other copyrighted material – launched a tirade against the Obama administration for its criticism of Sopa.

"So Obama has thrown in his lot with Silicon Valley paymasters who threaten all software creators with piracy, plain thievery," he wrote in a series of five tweets, accusing Google of hosting pirated material and selling advertising against it.

The White House statement was not a simple denunciation of Sopa and Pipa. It also makes clear that the administration is in favour of new legislation to combat online piracy, though the authors say it must be narrowly targeted. "Online piracy by foreign websites is a serious problem that requires a serious legislative response," they say.

The two bills have led to an outpouring of criticism from proponents of a free internet, Silicon Valley giants such as Google and Facebook, and start-up entrepreneurs.