Shares in BP tumbled to their lowest level since 1996 in US trading Wednesday on fears the company won't pay out its planned dividends to shareholders.
BP depositary shares trading in New York fell more than 15% to close at $29.20 - meaning the company's share price has now almost halved since the Louisiana oil spill began on 20 April.
Shares had already fallen more than 17p, or 4.2%, to 391.55p in London trading. BP stock is traded on the New York Stock Exchange after the FTSE 100 closes.
The US government yesterday signaled it will take legal action to force BP to stop paying a dividend to shareholders.
Associate Attorney General Thomas Perrelli said the Justice Department was "planning to take action" when asked at a Congressional hearing if an injunction was being considered against BP to stop the payout amid anger over the Gulf of Mexico spill.
President Barack Obama also suggested the oil giant should pay unemployment benefits to thousands of oil workers laid off during a moratorium on deep-sea drilling triggered by the spill.
BP responded to the sharp price fall in the US, stating that, "the company is not aware of any reason which justifies this share price movement".
The sharp fall in BP's share price is bad news for UK pension funds, which invest heavily in the firm.
The oil company has said it pays £1 in every £7 of dividends that the pension funds receive from FTSE 100 companies.
Obama has been accused of holding "his boot on the throat" of British pensioners after his attacks on BP were blamed for wiping billions off the company's value.
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