Updated

Massachusetts Rep. Ed Markey on Sunday released an internal BP document that shows the oil spill could spew 100,000 barrels a day into the Gulf of Mexico, far more than has been estimated in public accounts.

The worst-case scenario is based on what would happen if the damaged wellhead were removed and not capped. The document showed a low-ball estimate of 55,000 barrels per day.

Click here to read the document.

Markey, who's been a vocal critic of the oil giant, said BP has been unscrupulous since the start of the crisis.

"Right from the beginning, BP was either lying or grossly incompetent. First they said it was only 1,000. Then they said it was 5,000 barrels. Now we're up to 100,000 barrels," Markey said on NBC's "Meet the Press."

"It was their technology. It was their spill cam. They are the ones that should have known right from the beginning and, either to limit their liability or because they were grossly incompetent, they delayed a full response to the magnitude of this disaster," he said.

BP spokesman Toby Odone on Sunday told Reuters that he did not believe the company had underestimated the size of the spill.

"We've always said we would deal with whatever volume of oil was being spilled, and that's exactly what we're doing. We've mounted the biggest spill response in history."

Markey, the Democratic chairman of the House Energy and Commerce Subcommittee on Energy and the Environment, said that BP knew long before the explosion at the Deepwater Horizon rig that it had problems with cementing, leaks in the blowout preventer and gas kicks.

Adm. Thad Allen, the national incident commander leading the government's response to the spill, said Thursday that the condition of the wellbore, or the hole drilled to reach the oil field, is still unknown and is the reason that other failed efforts to cap the well weren't more rigorous.

"This document raises very troubling questions about what BP knew and when they knew it. 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," Markey said in a statement released with the document.

"BP needs to tell us what it will do if the wellbore is compromised and 100,000 barrels per day of oil spills into the ocean. At this point, we need real contingency planning," Markey added.