BP believes its Gulf of Mexico oil spill was only about half as bad as the US government estimates, according to officials investigating the accident.
The White House commission said the energy giant is arguing that the flow rate was closer to 30,000 barrels per day rather than the 60,000 guessed by government scientists.
This would put the total size of the spill at 2m barrels instead of the 4m barrels currently held as the best measurement.
It is understood that BP has been agitating for access to the oil well’s blow-out preventer, the safety device that failed and was later confiscated as evidence by US authorities. This could help its engineers back up their theory that the flow rate is 20pc-50pc lower.
The flow rate is important because BP is likely to be fined according to the volume of oil that spilled into the Gulf, after the Deepwater Horizon well exploded and sank killing 11 men on April 20.
Under the Clean Water Act, the government could fine BP up to $4,300 for each barrel of oil spilled into the Gulf, if negligence is proven or lower amounts for lesser charges.
“The relevance of how much oil was released obviously plays into the calculation of fines,” said Terry Garcia, a member of the commission. “It’s not surprising they think it was lower.”
The panel is currently looking at proposals to force companies to estimate flow rates more accurately early on, because this could help them tackle the spill better.
BP has been criticised previously for trying to deal with the erupted well using caps unlikely to work for such a strong flow.
Meanwhile, Rockhopper, the only Falkland Islands explorer with a profitable oil find, fell 3pc as leaked US diplomatic cables claimed drilling in the region is not commercially viable.
The Wikileaks documents show US officials discussing the possibility of tension escalating between Britain and Argentina over any oil find.
“ExxonMobil chairman Brad Corson told us he does not believe there is enough oil in the [Falklands] to be profitable, citing Shell (LSE: RDSB.L – news) ‘s earlier oil exploration attempts which they abandoned,” it said.