Lundin took its all-cash offer of C$4.75 per share directly to Nevsun shareholders on July 26, after its five previous proposals were rejected by the company.

Vancouver-based Nevsun said on Thursday it has entered into confidentiality agreements with 18 interested parties, and has received four proposals from mining and smelting companies, indicating their willingness to purchase up to a 19.9 percent equity interest in Nevsun.

The interested parties have also shown willingness to partner and develop the company's Timok copper project in Serbia.

Nevsun previously said, Lundin's offer undervalues the miner's Bisha mine in Eritrea and the Timok project and had cited a recent prefeasibility study, which valued the Serbian copper project at $1.82 billion.

(Reporting by Susan Taylor and Laharee Chatterjee in Bengaluru; Editing by Anil D'Silva and Shounak Dasgupta)