BHP Billiton has become the latest target of activist investors who have urged the miner to demerge its petroleum assets, downgrade its ASX listing and collapse its dual-listed company structure in a bid to release greater value.

In a proposal that could fall foul of Foreign Investment Review Board (FIRB) conditions applied to BHP's 2001 merger with Billiton, New York based Elliott Associates wrote to BHP directors, shareholders and media arguing the changes could liberate 48 per cent more value for BHP's Australian shareholders and slightly more for the company's London shareholders.