"It is an option," the source said, adding it was not likely that new equity would be raised. No decision has been taken.

Glencore listed on the London market in 2011, with a secondary listing in Hong Kong, marking the end of almost four decades as a privately held firm. It listed in South Africa late last year to attract funds trapped by caps on foreign investment.

(Reporting By Clara Ferreira-Marques; editing by Keiron Henderson)