About 1,800 workers are trapped underground at a Sibanye Gold Ltd. platinum operation in South Africa after an incident in the shaft used to transport workers, the company said.

The company may use an adjacent shaft to hoist the workers to the surface, although there's currently no estimate for when that may happen, a spokesman said.

Some rails being transported underground fell down the shaft and have blocked it, said spokesman James Wellsted. Sibanye is assessing the shaft infrastructure, which may take a couple of hours, he said. There were no injuries as a result of the accident.

The workers entered the mine this morning and the incident happened around lunch time, around when they'd normally be ending their shift, he said.

The incident may revive concerns about safety at Sibanye, which last year experienced a spike in fatal accidents. About 1,000 workers were also trapped underground for more than a day at one of its gold mines in February 2018 after a power failure.