The NSW Department of Planning and Environment was notified about the withdrawal, which occurred on Wednesday.

The DPE issued a prohibition notice and expressed broader concern regarding the recent gas exceedance events and the operating practices of the Illawarra Metallurgical Coal operation.

South32 confirmed that there was no gas exceedance or breach of gas limits.

But the reassurances were not enough for the DPE, which is taking a hard line on gas exceedances.

“Safety is a core value and we are working, together with the regulator, to address these issues,” South32 said.

The Dendrobium mine remains in operation.

Given the timing of the suspension, South32 said guidance for the 2017 financial year – which ends today – remained on track with 7.05 million tonnes produced up until Wednesday and 7.32Mt sold.

RBC Capital Markets had forecast production and sales for FY17 of 7Mt and 7.5Mt respectively.

It remains unclear on when the mine will restart, and South32 said it would provide guidance in August.

This is the third prohibition notice for Appin this financial year, with guidance already downgraded three times prior from the original figure of 9Mt.

Shares in South32 dropped by 1.2% to A$2.725 this morning.