The Rustenberg platinum mine, around 150 kms (93 miles) from Johannesburg, is one of the company's largest.

"There was an incident on the ore transportation system in the shaft. All our safety systems kicked in and nobody was seriously injured," company spokesman Johan Theron told Reuters.

Implats said it was attending to the injured workers who were at the bottom of the shaft when the incident occurred.

The spokesman said he could not give the exact number of workers injured or the extent of their injuries but said they were aware of at least two who had sustained minor injuries.

The Association of Mineworkers and Construction Union (AMCU), the majority union in the platinum sector, said four miners had been injured in the incident.

The injured workers would be brought up via an alternative shaft after medical officials attended to them, Theron said.

Investors have often raised concerns on poor safety records in South African mines, some of them the deepest in the world, and have been one of the factors why mining companies in the country trade at a discount to their global peers.

In 2019, South Africa saw a record low number of mine deaths at 51, versus 81 reported the previous year.

Implats said it would be conducting a systems check before transport of ore or employees on the shaft can resume, which it anticipated could take a day or two.

The affected shaft accounts for around 10% of the Rustenberg mine production.

(Reporting by Tanisha Heiberg; Editing by Promit Mukherjee and Emelia Sithole-Matarise)