A discovery of 6.8 Mt (7.5 million st) of rare earth elements by a team from Tokyo University could be large enough to supply Japan and its high-tech manufacturing industry for years to come.

The discovery is in an area near Minamitorishima Island in Japan’s exclusive economic zone.

Professor Yasuhiro Kato told AFP that he estimated at least 400 years work of Japanese consumption of dysprosium is contained in the deposit, located 5,600 m (18,000 ft) to the seabed.

Mud samples taken for analysis from mud in four locations from sea beds about 5,600 m to 5,800 m (18,000 ft to 19,000 ft) deep.  Rare earths minerals, with an average concentration ranging from 1,000 ppm or 0.1 percent to as high as 1,700 ppm, were found in 30-m- (100-ft-) thick mud about 310 km (192 miles) southwest of Minamitorishima.

It is estimated that beds of mud containing rare earth minerals are spread over a wide area of 1,000 square miles in the sea.

"I would like to see the Japanese government recognize the existence of the rare earth deposits and soon start making in investment in developing the area," said Kato.

"We can start drilling in the mud, using oil extraction technology, within three years at the earliest and start producing rare earth minerals within five years," he added.

The discovery would be the first large-scale rare earth deposit within Japanese territory.

However, in a news conference Japan's Minister of Economy, Trade and Industry Yukio Edano said, "This is welcome news. But the professor also says that a more detailed survey is necessary and that technology has to be developed to make commercial development possible."

Edano said the ministry has been planning on conducting its own survey of the area and will cooperate with Kato and others.