South Korea's largest mobile operator is launching what it says is the world's fastest wireless network.

SK Telecom has launched a new generation mobile network that offers speeds twice that of its existing long-term evolution (LTE) network and 10 times that of 3G services.

The new LTE-Advanced, which will be immediately available in Seoul and 40 other cities, will allow users to download an entire movie in about 40 seconds.

The network was launched on Wednesday in conjunction with a new LTE-A capable version of Samsung's flagship Galaxy S4 smartphone, and SK Telecom said half-a-dozen other compatible smartphones were expected to be offered in the second half of 2013.

'LTE-A will... give birth to new mobile value-added services that can bring innovative changes to our customer's lives,' said Park In-Sik, president of Network Business Operations at SK Telecom.

The company plans to use the new network to launch a group video-calling service for up to four users which it claims will boast 12 times better video quality and audio quality twice as clear than any existing service.

One of the most wired countries on earth, South Korea already has around 20 million 4G users.

In May, researchers at Samsung Electronics said they had successfully tested super-fast 5G wireless technology that would eventually allow users to download an entire movie in one second.

The South Korean giant said the test had witnessed data transmission of more than one gigabyte per second over a distance of two kilometres.

However, the new technology will not be ready for the commercial market before 2020 at the earliest.