Nippon Steel & Sumitomo Metal Corp. said Wednesday it will halt operations of blast furnace and production lines at its four iron mills in Japan as part of efforts to streamline its business.

Nippon Steel plans to close one of three furnaces at its mainstay iron mill in Chiba Prefecture by March 2016, and halt operations of 14 production lines at iron mills in four prefectures — Ibaraki, Chiba, Aichi and Wakayama.

The company will postpone the start of operations at its newly built furnace in Wakayama from this month, as originally planned.

The steelmaker will boost operation ratios at other mills and aim to bring back its output levels to the current levels in three years.

"We will aim to achieve the world's top competitiveness," Nippon Steel President Hiroshi Tomono said at a press conference as the company announced its medium-term business plan, adding the steelmaker is looking to invest more in emerging economies, including India and Brazil.

Nippon Steel also said it will generate about ¥300 billion by selling real estate and stocks to repay some of its debts stemming from a drop in prices of steel and escalated materials prices.