Chinalco will offer material concessions to its proposed $19.5bn investment in Rio Tinto in a late attempt to secure regulatory clearance from the Australian government and win the support of the Anglo-Australian group’s hostile shareholders.

The state-owned aluminium group is prepared to recast the deal to limit its stake in Rio to 15 per cent, down from the 18 per cent it hoped to secure when it agreed to buy $7.2bn of convertible bonds in February. Chinalco’s current stake is 9 per cent and the Chinese group also wants to invest $12.3bn for a large minority stake in Rio’s mining assets.