New Zealand miner Solid Energy has stopped production at the Huntly East Mine after inspectors identified a build-up of lethal gas.
Stuff reports Solid suspended operation last night but was confident its mines were operating safely.
The company told Stuff it was expecting mining to restart at Huntly East soon after it supplied a brief to inspectors.
Late last year reports surfaced staff at the same site had put rags over the mine's methane sensors in order to maintain production.
The sensors are designed for safety underground and automatically switch off machinery if gas levels reach a certain level.
Last year Solid Energy bought New Zealand's Pike River mine, where a series of underground explosions killed 29 workers in 2010.