Japan's biggest steel maker, Nippon Steel & Sumitomo Metal Corp., said Monday it will buy rival Nisshin Steel Co. in an attempt to withstand deteriorating conditions in the industry triggered by China's economic slowdown.

Nippon Steel, which already owns around 8 percent of Nisshin Steel, the fourth-largest player in the domestic market, plans to increase its stake to somewhere between 51 percent and 66 percent, turning Nisshin Steel into a subsidiary around March 2017.

The two firms have booked more than ¥6 trillion ($49.5 billion) in combined sales.