JX Nippon Mining & Metals, through its unit Japan Korea Joint Smelting, has agreed to divest its entire stake in South Korea’s copper smelter ls -Nikko Copper to its partner LS Corp (LSC) for $727m (KRW930bn).

South Korea’s only copper smelting company LSC currently owns a 50.1% stake in the smelter while Japan Korea Joint Smelting holds the remaining 49.9% stake.

Japan Korea Joint Smelting is 80% owned by JX Nippon Mining & Metals, which is a unit of Japan’s oil and metals giant Eneos.

Mitsui Mining & Smelting and Marubeni each own 10% of Japan Korea Joint Smelting.

JX Nippon said the decision to sell shares in LSN follows a thorough examination from various perspectives of its base business, which supports the company’s organisational basis, including copper smelting and refining.

Following the investigation, the firm determined it was necessary to sell LSN shares, and shift focus in its management resources on areas that are ‘deemed more important’.

The sale also comes due to reduced smelting margins for the Japanese firm caused by competition with larger rivals in China, according to Reuters.

In a press statement, JX Nippon said: “While we strengthen the ‘base business’ through this divestiture, at the same time, the JX Nippon Mining & Metals Group is steadily taking steps to further expand the ‘focus business’ centred on the advanced materials field.”