Google revealed top-secret plans Saturday to send balloons to the edge of space with the lofty aim of bringing Internet to the two-thirds of the global population currently without web access.

Scientists from the technology giant released up to 30 helium-filled test balloons flying 20 kilometres (12.4 miles) above Christchurch in New Zealand Saturday, carrying antennae linked to ground base stations.

While still in the early stages, Project Loon hopes eventually to launch thousands of balloons to provide Internet to remote parts of the world, allowing the more than four billion people with no access to get online.

It could also be used to help after natural disasters, when existing communication infrastructure is affected.

"Project Loon is an experimental technology for balloon-powered Internet access," the company said on its latest project from its clandestine Google (x), "where we work on radical, sci-fi-sounding technology solutions to solve really big world problems".

"Balloons, carried by the wind at altitudes twice as high as commercial planes, can beam Internet access to the ground at speeds similar to today's 3G networks or faster," it added.

"It is very early days, but we think a ring of balloons, flying around the globe on the stratospheric winds, might be a way to provide affordable Internet access to rural, remote, and underserved areas down on earth below, or help after disasters, when existing communication infrastructure is affected."

It works by ground stations connecting to the local Internet infrastructure and beaming signals to the balloons, which are self-powered by solar panels.

The balloons, which once in the stratosphere will be twice as high as commercial airliners and barely visible to the naked eye, are then able to communicate with each other, forming a mesh network in the sky.

Users below have an Internet antennae they attach the side of their house which can send and receive data signals from the balloons passing overhead.

Some 50 people were chosen to take part in the trial and were able to link to the Internet.

The first person to get Google Balloon Internet access was Charles Nimmo, a farmer and entrepreneur in the small town of Leeston who signed up for the experiment.

He told the New Zealand Herald he received Internet access for about 15 minutes before the transmitting balloon he was relying on floated out of range.

"It's been weird," he told the newspaper. "But it's been exciting to be part of something new."

Google's ultimate goal is to have a ring of balloons -- each the length of a small light aircraft when fully inflated -- circling the Earth, ensuring there is no part of the globe that cannot access the web.

But Richard DeVaul, chief technical architect at Google (x), cautioned that "it's awfully too early to think about covering the entire planet".

The next step might be to make a ring of balloons around the same latitude as New Zealand, he added, to extend coverage to countries such as Australia, South Africa and Argentina.

"We think hundreds of balloons, maybe 300 or 400, might be necessary to complete that ring," DeVaul said.

Google did not say how much it was investing in the project.

"The idea may sound a bit crazy - and that's part of the reason we're calling it Project Loon - but there's solid science behind it," Google said, but added: "This is still highly experimental technology and we have a long way to go."

Project leader Mike Cassidy told reporters that if successful, the technology might allow countries to leapfrog the expense of installing fibre-optic cable.

"It's a huge moonshot, a really big goal to go after," he said.

"The power of the Internet is probably one of the most transformative technologies of our time."