South32 chief executive Graham Kerr says the mining company is dealing with a "long term cultural issue" at its Illawarra Metallurgical Coal business in New South Wales, where it has faced operational problems and a controversial unfair dismissal ruling.

Speaking after South32's annual meeting in Perth on Thursday, Mr Kerr said Illawarra, which was a BHP operation before South32's 2015 demerger from the mining major, was "a longstanding operation that has had a culture that developed over many decades" and South32 was determined to overhaul it.