US President Barack Obama would be granted powers to seize control of and even shut down the internet under a new bill that describes the global internet as a US "national asset".

Local lobby groups and academics have rounded on the plan, saying that, rather than combat terrorists, it would actually do them "the biggest favour ever" by terrorising the rest of the world, which is now heavily reliant on cyberspace.

The proposed legislation, introduced into the US Senate by independent senator Joe Lieberman, who is chairman of the US Homeland Security committee, seeks to grant the President broad emergency powers over the internet in times of national emergency.

Titled "Protecting Cyberspace as a National Asset Act", the bill stipulates any internet firms and providers must "immediately comply with any emergency measure or action developed" by a new section of the US Department of Homeland Security, dubbed the "National Centre for Cybersecurity and Communications".

Lobby group TechAmerica told ZDNet it worried that the bill would give the US "absolute power" over the internet and create "unintended consequences".

One of Australia's top communications experts, University of Sydney associate professor Bjorn Landfeldt, railed against the idea, saying shutting down the internet would "inflict an enormous damage on the entire world".

He said it would be like giving a single country "the right to poison the atmosphere, or poison the ocean".

"All our financial systems, all our security systems ... we're so reliant on the internet that if you shut it down there's a question of whether society will continue to operate normally anywhere in the Western world," Landfeldt said in a phone interview.

"By doing this they would do the terrorists the biggest favour ever because they would terrorise the rest of the world".

Landfeldt said the US would be the only country in the world with the ability to shut down the internet. He said such a move would be extremely difficult for the US to justify to other nations.

"Unfortunately, too much of the core of the internet resides in the US - let's put it this way, they cannot shut down machines in Australia, but they can completely isolate us and shut down certain core functions like the DNS ... they can render the internet fairly useless for the rest of the world," he said.

Senator Susan Collins, co-sponsor of the bill, has said: "We cannot afford to wait for a cyber-9/11."

Lieberman argued the bill was necessary to "preserve those networks and assets and our country and protect our people".

He said that, for all its allure, the internet could also be a "dangerous place with electronic pipelines that run directly into everything from our personal bank accounts to key infrastructure to government and industrial secrets".

US economic security, national security and public safety were now all at risk from new kinds of enemies, including "cyber warriors, cyber spies, cyber terrorists and cyber criminals".

Geordie Guy, spokesman for the online users' lobby group Electronic Frontiers Australia, said governments around the world seemed terrified of some unidentified risk that they believe the internet poses.

"The proposal is from Joe Lieberman, a repeat offender on rights versus regulation, in a bill called Protecting Cyberspace as a National Asset Act of 2010," he said.

"One wonders which nation Senator Lieberman considers the internet an asset of, and how proposing its destruction by presidential or homeland security order protects it.

"The internet is not a national asset of the United States, nor is it a media regulation problem of Australia. It is an international network used by millions upon millions of citizens and it needs to remain free and available."

Communications Minister Stephen Conroy did not respond to calls requesting comment.

Google, one of the world's biggest internet companies, declined to comment as it was not yet official US government policy.