When Swiss-based Xstrata made a A$7.4m bid for WMC in October, the Melbourne mining group was far from happy.

The Australians said the offer grossly undervalued Olympic Dam, a copper and uranium mine in the South Australia outback. With spot prices for yellowcake oxide - the main uranium grade - having risen 49 per cent in the year to November in nominal dollar terms, and global production satisfying just 58 per cent of demand from nuclear reactors, WMC wants a better offer.