JOHANNESBURG, Nov 21 (Reuters) - South Africa's third-biggest telecom company Telkom said on Tuesday that it is in exclusive negotiations with a preferred bidder regarding the potential sale of its masts and towers business, Swiftnet.

Telkom said the preferred bidder is a consortium of equity investors, including a Black Economic Empowerment partner, led and managed by a reputable private equity firm. (Reporting by Nqobile Dludla; Editing by Edmund Klamann)