TOKYO (Kyodo) -- A Japanese project to secure critical minerals from deep waters off Minamitori Island in the Pacific has identified multiple types of medium and heavy rare earth elements that are integral to high-tech products, a government-affiliated research institute said Friday.

Medium and heavy rare earth elements such as yttrium, gadolinium and dysprosium accounted for approximately 54 percent of the total extracted from mud samples, while light ones such as neodymium made up the remaining 46 percent.

The Japan Agency for Marine-Earth Science and Technology did not disclose the total amount of rare earth elements collected from the mud samples.

Based on the results, the team plans to conduct a full-scale mining test in the same area for about a month starting in February and the government will assess the costs and benefits of industrialization by March 2028.

"It is extremely valuable for us to see yttrium especially, as its value has been soaring rapidly in the global market," project leader Shoichi Ishii of the Cabinet Office said at a press conference.

Japan faces the challenge of diversifying rare earth suppliers, as most of them come from China. Amid souring diplomatic ties over Prime Minister Sanae Takaichi's remarks on how Japan might respond to a crisis over Taiwan, China has tightened its controls on exports to the neighboring country of dual-use items that have both civilian and military applications, including rare earths.

Japan is seeking to domestically produce rare earths, which are critical in producing everything from electric vehicles and semiconductors to defense equipment.

Under the Cabinet Office project that began in fiscal 2018, JAMSTEC's Chikyu vessel collected about 50 tons of mud at a depth of about 5,600 meters around Minamitori Island, located some 1,900 kilometers southeast of Tokyo in the Pacific Ocean, in January and February.

For about a month from February 2027, the team aims to collect approximately 350 tons of mud per day, which will be transported to Minamitori Island for dewatering. It will be refined into rare earth elements on the main island.

The cost of extracting rare earths is seen as a challenge, as necessary personnel must be transported to the remote island by airplane or other means.

Chief Cabinet Secretary Minoru Kihara said the presence of high-quality rare earths in Japan's exclusive economic zone will allow Japan to reduce its excessive dependence on a specific country for critical minerals while enhancing its self-reliance.

"The government will immediately proceed with further tests for industrial-scale development," the top government spokesman said at a press conference.

(By Seiichiro Higuchi)