The men were travelling in a Land Rover when it was run over by a large dump truck operating at the Chalmerston/Pennyvenie opencut coal site, owned by Scottish Coal.
A spokesman for the Scottish Ambulance Service said the two men died at the scene.
“On behalf of all at Scottish Coal we would like to extend our deepest sympathies to the families, friends and work colleagues of the two men,” managing director of Scottish Coal Andrew Foster said.
“A full investigation of the incident has been launched. The site has been closed and will remain so until the investigation is complete."
The Chalmerston/Pennyvenie site, which employs 140 workers, is part of the East Ayrshire Coalfield Initiative, involving the areas around Cumnock, New Cumnock, Muirkirk and Dalmellington, where communities have been devastated by the decline of the deep mining industry, the Herald reported.