There had been speculation that relief wells could be completed ahead of schedule, but US Interior Secretary Ken Salazar stuck to the original timetable as fears grow that hurricanes and high waves could hinder efforts to stop the flow of 60,000 barrels per day.
BP shares were up 5pc at 318.9p in London, after Tuesday's note from JP Morgan Cazenove suggesting Exxon Mobil as a buyer triggered renewed optimism about the stock's value.