Shareholders in Anglo American voted to approve the global miner's $5.1 billion acquisition of an additional 40 percent stake in De Beers, bringing the company closer to sealing control of one of the world's biggest diamond firms.

South Africa's Optimum Coal Holdings confirmed on Friday it had received expressions of interest from unnamed third parties, a day after sources close to the deal said commodities trader Glencore was eyeing the miner. Optimum, South Africa's sixth-largest coal producer, said in a statement it had received "unsolicited, non-binding expressions of interest from third parties to acquire a controlling interest in Optimum".