JOHANNESBURG (Commodity Online): Yet another problem hit the gold mining business in South Africa with four illegal miners were killed in a shooting at an abandoned gold mine owned by relatives of former president Nelson Mandela and President Jacob Zuma.

Mining industry in South Africa has been reeling under safety problems for the past several months and this latest deaths are bound to create hurdles in the mining sector in South Africa.

Recently following deaths in a mine in China, mining operations were suspended at the mine in China.

The South African mine had been shut down amid complaints from workers that they had not been paid for months. It's co-owned by a grandson of Mandela and a nephew of Zuma through a firm called Aurora Empowerment Systems.

Aurora confirmed that there had been an exchange of gunfire, but would not state if its security guards had opened fire. It said the company was trying to protect its assets against trespassers.

Reports said security guards at the mine east of Johannesburg had opened fire on a group of illegal miners, leaving as many as 20 dead underground.

An Aurora director defended the security guards, saying the company had to protect its assets against armed trespassers.

The National Union of Mineworkers also called for an investigation, saying the dead may have been former Aurora employees who resumed mining on their own after going unpaid for months and then being left jobless when the mine closed.

Illegal mining in the bowels of South Africa's abandoned pits has long plagued the world's third-largest gold producer, with diggers -- known as 'zama zamas' (try, try) -- sometimes living for months underground to smuggle the precious metal.