MARIKANA, South Africa (Reuters) - World No. 3 platinum producer Lonmin said around 6,000 workers had gone on an illegal strike on Tuesday at its Marikana mine, which was the site of deadly labor violence last year that rocked Africa's largest economy.
The strike at the mine where 34 workers were shot dead by police last August - in the deadliest security incident since the end of apartheid in 1994 - also coincided with a visit by journalists to the site northwest of Johannesburg.
"This is the largest number of people who have refused to go underground since the end of the strike in August. It's illegal. It's not sanctioned," Mark Munroe, Lonmin's head of mining, told reporters.
Lonmin said the protests were being carried out by miners affiliated with the militant Association of Mineworkers and Construction Union (AMCU), who were demanding the closure of the offices of the rival National Union of Mineworkers because it was no longer the majority union.
The turf war between AMCU and NUM, which is a powerful political ally of the ruling African National Congress, was at the heart of much of the unrest that hit the platinum and gold mining sectors in South Africa last year, triggering labor violence that killed over 50 people.
The union rivalry has also shaken investor confidence in the world's top platinum producer and led to credit downgrades for the country.
Lonmin's share price in Johannesburg fell more than 1 percent on the news, underperforming the wider All-share index which was 1.19 percent higher.
(Reporting by Sherilee Lakmidas; Writing by Ed Stoddard; Editing by Jon Herskovitz)