TOKYO: Sediment containing rare earth was retrieved from ocean depths of 6,000m on a Japanese test mission, the government said on Monday (Feb 2), as it seeks to curb dependence on China for the valuable minerals.

Japan says the mission was the world’s first bid to tap deep-sea rare earths at such a depth.

"Details will be analysed, including exactly how much rare earth is contained" in the sample, government spokesman Kei Sato said, calling it "a meaningful achievement both in terms of economic security and comprehensive maritime development".

The sample was collected by a deep-sea scientific drilling boat called the Chikyu that set sail last month for the remote island of Minami Torishima in the Pacific, where surrounding waters are believed to contain a rich trove of valuable minerals.

It comes as China - by far the world’s biggest supplier of rare earths - ramps up pressure on its neighbour after Prime Minister Sanae Takaichi suggested in November that Tokyo may react militarily to an attack on Taiwan, which Beijing has vowed to seize control of by force if necessary.

Beijing has blocked exports to Japan of "dual-use" items with potential military uses, fuelling worries in Japan that Beijing could choke supplies of rare earths, some of which are included in China’s list of dual-use goods.

Rare earths - 17 metals difficult to extract from the Earth’s crust - are used in everything from electric vehicles to hard drives, wind turbines and missiles.

The area around Minami Torishima, which is in Japan’s economic waters, is estimated to contain more than 14.5 million tonnes of rare earths, which the Nikkei business daily says is the third-largest reserve globally.

These rich deposits contain an estimated 730 years’ worth of dysprosium, used in high-strength magnets in phones and electric cars, and 780 years’ worth of yttrium, used in lasers, the Nikkei said.

"If Japan could successfully extract rare earths around Minami Torishima constantly, it will secure domestic supply chain for key industries," Takahiro Kamisuna, research associate at The International Institute for Strategic Studies (IISS), told AFP.

"Likewise, it will be a key strategic asset for Takaichi’s government to significantly reduce the supply chain dependence on China."

Beijing has long used its dominance in rare earths for geopolitical leverage, including in its trade war with US President Donald Trump’s administration.

China accounts for almost two-thirds of rare earth mining production and 92 per cent of global refined output, according to the International Energy Agency.