The Department of Energy and Natural Resources has confirmed that a sinkhole has developed near Galmoy Mine in Co Kilkenny.
It was discovered in a field owned by farmer Eddie Cavanagh on Saturday morning, some 300 metres from the nearest building.
The Department added there are no public safety issues involved, but the mining company is maintaining 24 hour security at the scene and a nearby road has been closed as a precaution.
Officials from Kilkenny County Council and the Environmental Protection Agency are now liaising with the Department to work out what follow-up action to take.
The hole is believed to be about 10m (32ft) deep and 16m (53ft) in circumference.