TOKYO - JAPAN plans to start exploring its seabed to harvest rare earth elements used in electronics, hoping to reduce its heavy reliance on Chinese imports, a government official said on Tuesday.

Japan would also try to develop its capacity to extract badly needed energy resources such as oil, gas and methane hydrate in the project, which eyes test exploration by the 2018 fiscal year.

Japan is believed to have plentiful resources under the sea but it has not previously exploited them due to the prohibitive costs of developing the underwater technology.

China is the source of a vast amount of the world's rare metals, which are used in semiconductors and components for hybrid cars - key fields for Japanese companies.

'There is an increasing demand for mineral resources around the world, which has pushed prices higher,' said an official of the Japanese government's ocean policy headquarters.

'The combined area of Japanese waters and the country's exclusive economic zone is the sixth-largest in the world, despite the nation's small land mass,' he said.

Prime Minister Taro Aso's government aims to give the final go-ahead for the plan in March and to start implementing it in April, the official said.

Along with rare metals, Japan is estimated to have 5,000 years' worth of gold, silver and cobalt in its seabed along with 100 years' worth of methane hydrate, at current rates of usage.

Methane hydrate, a substance resembling ice, is believed to be rich in energy potential but scientists are still mastering ways to exploit it.

It is not yet known whether Japan's plan would involve parts of the East China Sea where Japan and China dispute undersea gas fields.

The row over the gas fields recently erupted again due to China's development of a gas field that Japan believed was still under negotiation. -- AFP