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. Former Lehman clients – notably hedge funds but also corporate clients – have been frantically calling for the return of their assets. However, PwC, administrator for Lehman's European operations, has warned it will likely take months to untangle the bank's holdings and commitments to a condition where they can begin returning assets.

Chinalco said there was no risk that its Rio shares would not eventually be returned as the holding was “held in a separate designated account” under a custody arrangement with Lehman Brothers International (Europe), the main operating body of the bank's European operations.

“There is no basis on which Chinalco's ownership of the shares could be validly challenged or on which its shares could form part of the general assets of LBIE,” said Chinalco. It added that it was discussing with Lehman's London administrators “the arrangements for the orderly transfer of the shares out of LBIE”.