Chinalco, Rio Tinto’s largest shareholder and one-time “strategic partner”, has given no indication of whether it will take up its rights in the miner’s $15.2bn (£9.2bn) rights issue, a factor contributing to Rio’s London-listed shares ending the week 20 per cent lower.

Rio’s UK shares, which are three-quarters of its dual-listed share capital, were expected to remain lower this week as the market digested its huge rights issue. The issue is injecting the equivalent of more than 30 per cent of its share capital into the market at half the price the shares were trading before the cash call.