BP has "fallen short" in providing data about the Gulf of Mexico oil spill, the US government has said, in its latest critical letter to the firm.
The Obama administration said the British energy giant should act in a "transparent manner" and "promptly" make all information public.
Earlier, BP said more oil than the 5,000 barrels a day it first estimated were gushing from the burst well.
The spill has reached Louisiana and is threatening Florida and Cuba.
The crude has been flowing since the offshore drilling rig Deepwater Horizon, leased by BP, exploded off the coast of Louisiana on 20 April and sank two days later.
'A little more'
The Obama administration asked BP to make public all measurements of the growing leak, air and water quality samples, trajectories of underwater plumes and locations of dispersants.
The request came in a letter to BP CEO Tony Hayward from Homeland Security Secretary Janet Napolitano and Environmental Protection Agency (EPA) Administrator Lisa Jackson.
It said: "In responding to this oil spill, it is critical that all actions be conducted in a transparent manner, with all data and information related to the spill readily available to the United States government and the American people."
The officials said that despite claims by BP it was making efforts to keep the public and the government informed, "those efforts, to date, have fallen short in both their scope and effectiveness".
They said it was "imperative that BP promptly" make public all data on the spill.
Obama administration officials last week wrote a letter to BP demanding clarification over its commitment to pay for damages from the spill; the firm said it had already done so.
Another letter at the weekend cast doubt over the effectiveness of BP's latest attempt to siphon oil from the gushing well head.
BP had stuck by its first estimate that some 5,000 barrels, or 210,000 gallons, a day of oil was leaking from the well - despite claims from several experts the real figure was at least 10 times higher.
But BP spokesman Mark Proegler told news agency AFP on Thursday: "Now that we are collecting 5,000 barrels a day, it might be a little more than that."
A live video feed showing the oil gushing from the well has been made available by BP after pressure from a US congressman.
It shows a large, flowing plume of oil and gas next to the tube that is carrying some of it to the surface.
Meanwhile, the EPA has told BP to use a new dispersant to contain the spill, as fears grow about potential damage from the use of such chemicals.
BP has used a number of dispersants, all approved by the EPA, to try to break up the crude.
The oil firm's temporary solution has been to funnel the oil up to a ship, but on Sunday it is preparing its latest attempt to seal the rupture, which is a mile below on the seabed.
Engineers are planning a so-called "top kill" operation, in which heavy mud would be injected to stem the oil flow, then cement used to block the well permanently.
It emerged on Wednesday a small portion of the slick had entered the so-called Loop Current, which could take it to Florida and up the eastern US coast.
Florida forecasters said it would be at least a week before the oil reached waters near the state.
Farther south, US officials have been talking to Cuba about how to respond should the spill reach the island's northern coast.