Anglo American Platinum warned investors on Monday that it may have plunged into a heavy loss last year, after fatal labour unrest hit its South African operations. In a profit warning -- filed with the Johannesburg Stock Exchange -- Amplats said that 2012 earnings would probably show a loss of 491 to 628 cents per share, down from a profit of 1,365 cents per share in 2011. The firm is expected to publish full end of year results on about February 4. \"Platinum sales volumes for the period were lower primarily due to the two-month illegal industrial action experienced during the second half of 2012,\" the company said. Miners demands for higher wages crippled production across South Africa\'s mining sector, and resulted in violence that killed at least 50 people amid a police crackdown. The strikes reduced Amplats production by around 306,000 ounces. The collapse of Amplats\' profits raises the spectre of wholesale restructuring and job losses. The company said that a reassessment of the value of its assets resulted in a write-down of 463 million rand ($53 million). Some of these assets, it said, are \"not economically viable in the current market environment.\" The warning marks a tough beginning for newly named chief executive Mark Cutifani, who was named to replace Cynthia Carroll earlier this month. Cutifani is no stranger to the problems of South Africa\'s mining sector, he was formerly CEO of South Africa-based gold producer AngloGold Ashanti. The sector has been plagued by over-reliance on cheap labour, high extraction costs and decades of low investment.