Grant Thornton Partner and lead administrator Said Jahani said the agreement was the result of a collective effort from a range of key stakeholders.

“We are very pleased to have reached an agreement with one of Delta’s largest customers that will see approximately 200 Delta employees return to work today,” he said.

“There is still a great deal of work to be done with regard to Delta’s overall position and further updates will be provided as information becomes available.”

A South32 spokesperson told Australia’s Mining Monthly: “We have reached an agreement with the administrators for current Delta employees based at our Appin mine to return to work.

“We will continue to work with the administrators through this process.”

Appin is under pressure to sustain production levels after South32’s Illawarra Metallurgical Coal subsidiary advised that its production in 2016-17 was expected to be at least 10% below prior guidance of 7.9 million tonnes because of previous production stoppages at Appin.

The company said that on May 7 elevated gas concentrations were recorded at Appin Area 7 and all personnel were safely evacuated.

“Production at the Area 7 and Area 9 longwalls, which form part of the broader Illawarra Metallurgical Coal operation, has been suspended until our investigation into the incident is completed,” it said.

“A revised production forecast for FY17 will be provided in due course, with the decrease expected to translate directly to sales given low inventory levels. A commensurate increase in unit costs is also anticipated.”

Illawarra Metallurgical Coal’s total saleable production fell 9% to 5.3Mt in the nine months ended March 2017 as challenging ground conditions were encountered at Appin Area 9.

Mining rates were also moderated at Appin Area 7 to ensure gas concentrations were maintained at safe levels.