AngloGold Ashanti ( JSE :ANG) and Gold Fields ( JSE:GFI ), South Africa's biggest gold producers, should separate their troubled mines in the country from their foreign assets, John Hathaway, the managing director of Tocqueville Asset Management LP, said. "I have advised the companies we know very well in South Africa that they should think of a way to separate their South African assets away from the rest of their portfolio," said Hathaway, who manages the $2.5 billion Tocqueville Gold Fund, on a conference call today. "There is an excessive discount on the assets they have outside of South Africa because of the news in South Africa." The South African mines of the two companies have been caught up in a wave of illegal and violent strikes that began at the Marikana platinum mine owned by Lonmin ( JSE:LON ) on Aug. 10. Workers, defying their main labor union, are demanding pay rises even though an existing pay agreement has not run its course.