* BP: Document estimate 'irrelevant' to current situation
* Internal document released by US Democratic congressman (Adds BP reaction, paragraphs 5-6, 11)
WASHINGTON, June 20 An internal BP Plc (BP.L) (BP.N) document released on Sunday by a senior U.S. congressional Democrat shows that the company estimates that a worst-case scenario rate for the Gulf of Mexico oil spill could be about 100,000 barrels of oil per day.
The estimate of 100,000 barrels (4.2 million gallons/15.9 million liters) of oil per day is far higher than the current U.S. government estimate of up to 60,000 barrels (2.5 million gallons/9.5 million liters) per day gushing from the ruptured offshore well into the sea.
The document, which is undated, was released by U.S. Representative Ed Markey, chairman of the energy and environment subcommittee of the House of Representatives Energy and Commerce Committee.
The amount of oil actually gushing from the well has been a matter of considerable controversy since the spill began on April 20, with critics saying BP has understated the flow rate.
BP spokesman Toby Odone said the document appeared to be genuine but the estimate applied only to a situation in which a key piece of equipment called a blowout preventer is removed.
"Since there are no plans to remove the blowout preventer, the number is irrelevant," BP spokesman Toby Odone said.
The document appears to estimate the highest potential flow of oil if key components of the well fail. The document does not indicate that the 100,000 barrels per day is BP's estimate of the actual amount flowing from the ruptured Gulf of Mexico well.
The document states, "If BOP (blowout preventer) and wellhead are removed and if we have incorrectly modeled the restrictions -- the rate could be as high as ~ 100,000 barrels per day up the casing or 55,000 barrels per day up the annulus (low probability worst cases)"
"This document raises very troubling questions about what BP knew and when they knew it," Markey said in a statement.
"It is clear that, from the beginning, BP has not been straightforward with the government or the American people about the true size of this spill. Now the families living and working in the Gulf are suffering from their incompetence," he added.
BP initially estimated that the spill was pouring 1,000 barrels per day into the ocean and then upped that figure to 5,000 barrels per day.
"Right from the beginning, BP was either lying or grossly incompetent," Markey told NBC's "Meet the Press" program. "First they said it was only 1,000 barrels, then they said it was 5,000 barrels."
Odone said, "I don't think there's been any underestimating. We've always said we would deal with whatever volume of oil was being spilled and that's exactly what we're doing."
The document was posted on the Internet here
(Writing by Will Dunham, additional reporting by Bruce Nichols in Houston and Thomas Ferraro in Washington; Editing by Sandra Maler)