Chinalco, China's biggest aluminium producer, has emerged as the latest company to have a key asset tied up in the collapse of Lehman Brothers, after it said yesterday that the failed bank was custodian of its 12 per cent stake in Rio Tinto's London-listed shares.

Earlier this month Olivant, the investment business run by Luqman Arnold, led the way when it said its entire 2.78 per cent stake in UBS was held in Lehman accounts, which also stopped it from voting the shares. Rio is currently the subject of hostile takeover interest from rival BHP Billiton, meaning voting interest on Rio's shares could be crucial.