Google announced plans Wednesday to build experimental ultra high-speed broadband networks that would deliver Internet speeds 100 times faster than those of today to up to half a million Americans.

The Web search and advertising giant said the envisioned one gigabit per second speeds would allow to stream 3-D medical imaging over the Web or download a high-definition, full-length movie in less than five minutes.

Google's project complements US President Barack Obama's pledge to bring broadband to every US home as part of the Federal Communications Commission's National Broadband Plan.

Google product managers Minnie Ingersoll and James Kelly said the Mountain View, California-based company was planning to "build and test ultra high-speed broadband networks in a small number of trial locations" in the United States.

"We'll deliver Internet speeds more than 100 times faster than what most Americans have access to today with one gigabit per second, fiber-to-the-home connections," they said in a blog post.

Google said it planned to offer service to at least 50,000 and potentially up to 500,000 people.

"Our goal is to experiment with new ways to help make broadband Internet access better, faster and more widely available," Richard Whitt, Google's Washington-based telecom and media counsel, said in a blog post.

"We think that ultra high-speed bandwidth will lead to many new innovations -- including streaming high-definition video content, remote data storage, distance learning, real-time multimedia collaboration and others that we simply can't imagine yet."

Google was not looking to compete with the telephone and cable television companies that are the current Internet Service Providers (ISPs), Whitt told AFP.

Rather, Google planned to offer a "paid service to customers at a competitive price," he said, but would focus on "underserved" communities or those that "have no service whatsoever."

"It's not intended to supplant (ISPs)," Whitt said. "It's Google thinking that we need to step back and look at the broadband space and see if there's anything we can do to make for better customer experience.

"We in the US are still lagging behind the rest of the world," he added, noting that some countries have 100 megabit per second home connections.

Whitt said there was no set date for having the service up and running. "If we can do it before 2011, great, but no timelines really," he said.

Google invited communities around the country that wanted to take part in the high-speed broadband trial to make their interest known by March 26 and said the target communities would be announced later this year.

FCC chairman Julius Genachowski welcomed the Google initiative, saying "this significant trial will provide an American testbed for the next generation of innovative, high-speed Internet apps, devices and services."

Ed Black, president and chief executive of the Computer and Communications Industry Association, also welcomed the move.

"We have been locked in a rut for too long about how we expand broadband deployment," Black said. "Some experimentation and new thinking by truly innovative companies, not just legacy providers, is long overdue and welcome."

The United States was ranked 20th in broadband penetration in a survey of 58 countries released last year by Boston-based Strategy Analytics.

Median US broadband speeds are less than 5.0 megabits per second (Mbps) -- capable of moving five million bits of data per second -- according to the Information Technology and Innovation Foundation, far slower than those of Japan (63 Mbps) and South Korea (49 Mbps).

Google's move into broadband is another departure from its core search business and its latest bid to increase access to the Web and, consequently, the services it provides.

The company has already requested the authority to buy and sell electricity in the United States and announced plans to invest hundreds of millions of dollars in "green" energy projects.

Its has deployed a number of free productivity tools on the Internet, its own Web browser, Chrome, and is engaged in a vast and controversial project to digitize and sell millions of books online.

Google is developing its own computer operating system, also called Chrome. A number of leading handset makers already use Android, its mobile telephone operating system.

Last month, the firm released its own smartphone, the Nexus One.

Google shares shed 0.37 percent on Wall Street to close at 534.44 dollars.