BHP Billiton, the world's biggest miner, is in talks with Harry Winston, the Canadian mining and retail group, about a sale of its diamond business, the Financial Times reported on Tuesday.

Harry Winston has secured bank financing for a possible deal and is continuing negotiations with BHP to buy the Ekati mine in Canada, the FT reported.

BHP could, however, opt to keep the unit as discussions drag on with the sole remaining bidder for its mine. The process, originally forecast to conclude by the middle of this year, is moving more slowly than expected and could fail to result in a deal, the report said.