Hollywood sparred with Silicon Valley in the US Congress on Wednesday at a hearing on a controversial bill intended to crack down on online piracy.

Internet search giant Google, an opponent of the legislation, was pitted alone against five supporters of the Stop Online Piracy Act (SOPA) at the three-and-a-half hour hearing of the House Judiciary Committee.

The bill has received the backing of the Motion Picture Association of America (MPAA), the Recording Industry Association of America, the Business Software Alliance, the US Chamber of Commerce and others.

But it has come under fire from digital rights groups and Internet heavyweights such as Facebook, Twitter and Yahoo!, as well as Google, who say it raises censorship concerns and threatens the very architecture of the Web.

The bill would give the US authorities more tools to crack down on foreign "rogue" websites accused of piracy of movies, television shows and music and the sale of counterfeit goods.

It would require Internet Service Providers (ISPs), search engines, payment providers and advertising networks served with court orders to block access or sever ties with websites accused of copyright or trademark infringement.

Opening the hearing, Lamar Smith, a Republican from Texas who chairs the Judiciary Committee and is a co-sponsor of SOPA, said "the problem of rogue websites is real, immediate and widespread.

"Since the United States produces the most intellectual property, our country has the most to lose if we fail to address the problem of these rogue websites," said Smith, who lashed out at Google from the outset accusing it of seeking to "obstruct" the bill.

"Perhaps this should come as no surprise given that Google just settled a federal criminal investigation into the company's active promotion of rogue websites that pushed illegal prescription and counterfeit drugs on American consumers," he said.

One of the witnesses backing the legislation, Michael O'Leary, senior executive vice president of the MPAA, said Google should be doing more to combat piracy.

"There are legitimate services out there now," O'Leary said, providing legal downloads or streams of movies and television shows.

"The problem is that when you go to Google and you punch in the name of a movie those legitimate sites are buried on page eight of the search results," he said.

"There is a better-than-average chance that Pirate Bay is going to end up ahead of Netflix," O'Leary said. "That's a fundamental problem no matter how many legitimate sites are out there that we can't overcome.

"If we could get Google to reindex those sites in a way that favored legitimacy... then consumers would be getting to those first," O'Leary said. "That's a practical problem that could be addressed today."

Reminding the panel at one point that Google does "not control the World Wide Web," the company's copyright counsel Katherine Oyama backed a "follow the money" approach to dealing with copyright and trademark infringers, choking them off from payment providers and from advertisers.

"If you can cut off their financial ties they won't have a reason to be in business anymore," Oyama said. "If you look at WikiLeaks that is how they've been taken out, by cutting off the money."

As for the bill in its current form, "there is a tremendous concern in the technology community about some of the remedies being proposed and some of the unintended consequences they would have," she said.

"Casting the net too broadly threatens collateral damage to legitimate businesses and activities online, while letting the rogues wriggle free," Oyama said.

Zoe Lofgren, a Democrat from California whose congressional district includes San Jose, home to many leading high-tech companies, expressed displeasure with the composition of the panel and the bill.

"We've got six witnesses here," Lofgren said. "Five are in favor and only one against and that troubles me.

"The point is that search engines are not capable of censoring the entire World Wide Web. We need to go after the people who are committing crimes in a way that would work. This bill would not do that."