Japanese steelmakers have raised concerns with Australian authorities that BHP Group could become too dominant in the global supply of coking coal if it goes ahead with a takeover of Anglo American.

Australia is the world's biggest exporter of coking coal and top supplier to Japan, making up around 60% of its imports, with most of the steelmaking ingredient coming from the state of Queensland, where BHP and Anglo American are the two largest producers.

Steelmakers' concerns about BHP's coking coal market power could derail a deal if the Australian giant comes back with a revised bid for Anglo American, after being rebuffed with a $39 billion offer last month.