Vale do Rio Doce and Xstrata have been in serious discussions about a potential $90bn (£46bn) cash and share takeover for more than two weeks, but the two mining groups seem to have reached an impasse.

The Brazilian group believes Xstrata is worth £40 to £42 a share, while Xstrata and its leading shareholder Glencore, which owns 35 per cent of the Anglo-Swiss miner, believes discussions should be held within the £45 to £48 a share range.