A consortium of six international companies, including Google, is to build an ultra high-speed submarine fibre optic cable system linking the US and Japan.

The Unity cable system will provide much needed capacity to sustain the increasing data and internet traffic between Asia and the US.

The six companies are Singapore Telecommunications Ltd, Bharti Airtel, Global Transit, Google, KDDI Corporation and Pacnet.

Unity is expected to cost around $300m and will initially increase trans-Pacific cable capacity by about 20 per cent.

The cable will link Chikura in Japan directly to Los Angeles in the US and is expected to be ready for service in the first quarter of 2010.

"Unity allows the members of the consortium to provide the increased capacity needed as more applications and services migrate online, giving users faster and more reliable connectivity," said Jayne Stowell, a spokeswoman for Unity.

Using state-of-the-art Dense Wavelength Division Multiplexing technology, the cable will support up to 960Gbps per fibre-optic pair with a maximum of eight fibre pairs.

The higher fibre count allows Unity to offer more capacity at lower unit costs. The cable will have a potential capacity of 7.68Tbps, making it one of the highest capacity cables of its kind.

"This new submarine cable network will be able to meet the strong demand for data, e-commerce and internet traffic between Asia and the US," said Mark Chong, executive vice president for networks at Singapore Telecommunications.

"As it is connected to other cable systems in Asia, it will also provide access to other parts of the region and serve as an important cable diversity route."

Trans-Pacific bandwidth demand grew at a compound annual growth rate of 63.7 per cent between 2002 and 2007, according to the TeleGeography Global Bandwidth Report 2007.

Demand is expected to continue to grow strongly from 2008 to 2013, doubling roughly every two years.

The Unity system will also provide a vital backup in case of network disruptions like those caused after two undersea cables in the Mediterranean were damaged.