South32 Limited (ASX: S32) updated that underground operations at the Appin colliery, which forms part of its broader Illawarra Metallurgical Coal operation, remain suspended. A review of the operation’s systems and operating practices is currently being undertaken to ensure its ongoing safety and reliability. Given the scope of this review, an extended outage is now anticipated before production at Illawarra Metallurgical Coal can be restored to historic levels, while the Dendrobium mine continues to operate and that production guidance for FY17 remains on track with Illawarra Metallurgical Coal having produced 7.05Mt (sales 7.32Mt) to 28 June 2017. Earlier, the company has announced that the production at Illawarra Metallurgical Coal in FY17 is expected to be at least 10.0% below prior guidance of 7.9Mt due to elevated gas concentrations at Appin Area. The company has informed the New South Wales Department of Planning and Environment (Resources Regulator) of the incident and a prohibition notice has been issued.