TOKYO (Reuters) - Global miner BHP Billiton and Japanese steelmakers have agreed on a 12.5 percent hike in the price of coking coal for the July-September period from the previous quarter, an industry source said yesterday.

The price hike to about $225 per tonne would represent a 75 percent rise from a year earlier for the key ingredient used in steelmaking.

Nippon Steel Corp, the world's No. 2 steelmaker, will likely seek to increase steel prices by an average 25,000 yen in July-September to pass on the rise in costs, the Mainichi newspaper reported.

Nippon Steel will aim to lift prices to 100,000 yen a tonne in talks with automakers and other customers, the paper said, adding that it was in late-stage negotiations for April-June to raise prices by 15,000 yen per tonne to about 90,000 yen.

Shares in Nippon Steel fell 0.9 percent to 316 yen, in line with the broader market.