Chinalco, Rio Tinto’s biggest shareholder, is widely expected to take up its full entitlement on Wednesday to new shares in the mining group’s $15.2bn (£9.2bn) capital raising.

Wednesday’s deadline will bring an end to lingering uncertainty over Chinalco’s intentions, which has persisted since the beginning of the month, when Rio’s board turned its back on a $19.5bn capital injection from Chinalco that would have increased the Chinese group’s stake to close to 19 per cent.