BP has admitted that the bill for the Gulf of Mexico spill has soared to £1.57bn.
The company said the sum included £84m paid out in claims to those affected by the disaster.
Progress on the relief well, intended to kill the leaking well, and measures to improve the capture of oil from the leaking well, were on track, BP said.
However, the stock fell more than six per cent to just above 300p after the figures on the bill were released. A report that tropical storms were heading to the spill zone, threatening the clear-up, also took its toll.
Chief executive Tony Hayward insisted the oil group's health had stabilised, despite still being in “intensive care”, when he met company staff yesterday.
But investors continued ditch shares.
BP has so far captured 364,500 barrels of oil through its containment system, but it is estimated that between 35,000 and 60,000 barrels a day are continuing to pour from the well.
The well ruptured after the Deepwater Horizon oil rig exploded on 20 April, killing 11 workers.