Rio has pledged to cut its $37bn debt burden by $10bn by the end of this year through asset sales, cost-cutting and delaying growth projects.
The group hopes to avoid a rights issue, but was forced to admit last week that it had not ruled it out. Rio's cash flows have been squeezed by the fall in commodity prices during the past six months, and it has failed to find buyers for several non-core assets it has been trying to sell since 2007.
Chinalco owns 12 per cent of Rio's London-listed shares and 9 per cent of the whole group, and said last year it was looking at increasing this stake. In recent weeks talks between the two sides have intensified.