Nippon Steel Corp. has sued South Korea's largest steelmaker, Posco, and other entities in Japanese and U.S. courts, claiming they illicitly obtained Nippon Steel's technology to manufacture material for use in products such as electric transformer cores and hybrid car motors.

In the suits, Nippon Steel is demanding that Posco stop marketing products that use its technology for grain-oriented electrical steel sheets. It is seeking about ¥100 billion in combined damages from Posco, its Japanese subsidiary and a former Nippon Steel employee it accuses of leaking the technology, Nippon Steel said Wednesday.

The Japanese steelmaker developed the technology to enhance the electric power transmission efficiency of the sheets in the 1990s, and its products account for about 30 percent of the global market for products using the material.

Nippon Steel has licensed steelmakers in Europe, China and the United States to use the manufacturing technology.