U.S. officials and high-tech business giants have launched an assault against what they view as a massive threat to the Internet and to Silicon Valley’s bottom lines: foreign governments.

In a congressional hearing Thursday, they will warn lawmakers of a growing movement led by China, Russia and some Arab states to hand more control of the Web to the United Nations and place rules on the Internet that the U.S. companies say would empower governments to clamp down on civil rights and free speech.

That could mean the Web might look drastically different in other countries than it does in the United States, opponents of the proposals say. An Internet user in Uzbekistan could be more easily tracked by government officials and might get access to only a portion of the Google search results seen in the United States, for example.

In a rare coordinated effort to knock down the proposals, Google, Microsoft, Verizon and Cisco also warn of financial risks to their businesses if new rules are adopted. They say some nations may push forlaws on Internet firms that could lead to tariffs on Internet service providers such as Verizon, or even Web firms such as Facebook that enable people to communicate over the Internet.

“The threats are real and not imagined, although they admittedly sound like works of fiction at times,” said Robert McDowell, a Republican member of the Federal Communications Commission.

The U.S. companies’ protests come ahead of a key December meeting in Dubai, where United Nations members will reconsider a 1988 communications treaty. Several foreign governments have argued that the treaty needs to be updated, given the growing influence of Internet communications.

The number of Web users is expected to grow from 2.3 billion today to 3.4 billion in four years, according to a new report by Cisco. Facebook and Twitter proved to be vital for revolutionaries during the Arab Spring protests last year. And in many developing countries, the only outlet to the outside world is what people read online.

“So much has changed since the 1988 revisions, so the global policy and regulatory framework needs to be updated,” Hamadoun Toure, secretary general of the International Telecommunications Union, the U.N.’s telecom authority, said in a speech this month.

Many nations want more say over the shape of the Web. The Internet has been heavily influenced by U.S. firms and American academics who set the standards, they argue. China, in particular, has been critical of the United States’ efforts to encourage open Web policies around the world.

The ITU has criticized the U.S. outcry against the proposals by foreign governments. “We are baffled. There is so much misinformation on this,” said Alexander Ntoko, head of corporate strategy for the ITU. He said the Americans are exaggerating how much the U.N. could shape the Web.

Still, U.S. officials have become alarmed at the language foreign leaders are using when they discuss what to do with the Internet.

Russian President Vladi­mir Putin, for instance, said last year he supported the idea of “international control over the Internet using the monitoring and supervisory capabilities” of the ITU.

Last September, Russia, China, Tajikistan and Uzbekistan wrote a letter to the U.N. General Assembly that called for an “international code of conduct” that would establish “norms and rules guiding the behaviour” of countries overseeing the Web.

In February, several Arab nations proposed that countries should be able to “take measures to ensure that fair compensation is received” for the flow of Internet traffic. Currently, no rules are in place for delivering Internet traffic globally. Telephone companies, in contrast, are required to pay fees to firms in foreign countries for international calls.

“Once upon a time, many countries in the developing world received billions of dollars in hard currencies for terminating telephone calls,” said David Gross, the former State Department coordinator of international communications policy now representing a coalition including AT&T, Cisco, Comcast, Google and Microsoft. “That money has disappeared.”

Russia has suggested cutting off access to the Internet for users who threaten network security. Arab nations have called for privacy protections for users, except for the purposes of law enforcement officials. “Such proposals raise the prospect of policies that enable government controls but greatly diminish the ‘permissionless innovation’ that underlies extraordinary Internet-based economic growth, to say nothing of trampling human rights,” said Vint Cerf, Google vice president and “chief internet evangelist.”