South32 may seek NSW government intervention over the rejection of a life extension for its Illawarra coking coal business and says the surprise decision is a reminder of how difficult coal approvals are in Australia.

Rejection of the mine extension has raised concerns about the viability of the nearby BlueScope steelworks at Port Kembla, and South32 chief executive Graham Kerr said the NSW process had denied his company the chance to counter claims against the project.