A Google spokesman Friday warned that a proposed new law that would force Italian Internet providers to block access to Web sites that incite or justify criminal behavior could threaten freedom of expression and prove unworkable in practice.

The new rule was proposed by Senator Gianpiero D'Alia, of the centrist UDC party, after newspapers reported that the social-networking site Facebook was hosting fan groups for imprisoned Mafia bosses Salvatore Riina and Bernardo Provenzano.

The bill, which gives the interior ministry the power to order Internet providers to block criminal content within 24 hours or face fines of between €50,000 (US$64,000) and €250,000 (US$321,000), was given initial assent in the Senate last week.

"The order is not directed at the content creator or the person running the platform but at the company that provides Internet connectivity," Marco Pancini, the head of institutional relations for Google Italy, said in a telephone interview. "Those companies are not in a position to remove a single item, so they would have to black out the entire platform."

The measure, originally aimed at Facebook, could also have dire consequences for YouTube, the video-sharing site owned by Google. "The law concerns all the Internet hosting platforms that host user-generated content. Our worry is about its possible effect on the entire Internet ecosystem," Pancini said.

The Google spokesman said the new rule was being rushed into law in response to the furor over the Mafia-praising Facebook sites without consultation with Internet operators and users. Pancini added he was worried that the law didn't specify who would conduct the monitoring of potentially illegal content or how it should be done.

"I have no idea what will happen if this bill is approved. There are already Europe-wide regulations governing online trade, which were introduced after consultation with the interested parties. This bill won't solve the problem and its consequences are difficult to predict," Pancini said.

D'Alia's bill calls on the interior ministry to consult with the ministries of economic development and public administration to define the technical requirements for filtering controversial content. "It's rather worrying that the filtering systems are not clearly defined in the law. Self-policing by the community, using the wisdom of the masses, is a better solution," Pancini said.

Facebook has also expressed anxiety about the new legislation. It was "akin to shutting down the country's entire railroad network because of some objectionable graffiti in one train station," Facebook spokeswoman Debbie Frost told the Bloomberg news agency Friday.