Shareholders in UK mining company Rio Tinto have reacted furiously to the company offering convertible bonds to Chinese state-owned metals group Chinalco in return for almost $20bn of fresh capital.

The shareholders' outrage is so great that some fund managers, such as the UK's Legal & General Investment Management, have spoken out in public against the deal - as some did last year when Barclays circumvented its rights issues by seeking capital from Middle Eastern institutions.