Johannesburg  - Seven miners were killed in an underground accident at a platinum mine in South Africa's North-West province and two more were missing, mining company Impala Platinum said Tuesday.

The accident, apparently caused by rockfall, took place Monday afternoon. The first bodies were only brought to the surface around midnight as rescue workers battled to reach the miners under rubble.

The National Union of Mineworkers said the chances of the two missing miners being found alive were almost nil.

An investigation is underway into the cause of the accident.

Dozens of miners are killed in accidents in South Africa each year. The country is the world's biggest platinum producer and third-largest gold producer.

Impala Platinum is the world's second-largest producer of platinum, a precious metal used in car manufacturing and jewellery. (dpa)