VENICE, La./WASHINGTON (Reuters) - The U.S. government Thursday accused energy giant BP of falling short in the information it has provided about the Gulf of Mexico oil spill, in a clear sign of Washington's growing frustration with BP's handling of the spiraling environmental disaster.
"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," Homeland Security Secretary Janet Napolitano and Environmental Protection Agency Administrator Lisa Jackson said in a letter.
The officials said in a letter to BP CEO Tony Hayward that despite claims by BP that it was striving to keep the public and the government informed, "those efforts, to date, have fallen short in both their scope and effectiveness."
The statement followed allegations earlier in the day that BP had engaged in a "cover-up" about the extent of the damage and the amount of crude flowing unchecked from its ruptured well in the Gulf of Mexico.
TV images of oil sloshing into Louisiana's marshes has underscored the gravity of the situation and raised public concern and anger about the unfolding catastrophe, keeping it high up on the political agenda in Washington.
BP shares closed up one percent Thursday but the markets have raked around $30 billion from its value in the month since the rig explosion, which killed 11 workers and sparked the disaster-in-the-making.
BP said Thursday it was siphoning 5,000 barrels (210,000 gallons/795,000 liters) per day of oil from the gusher, from 3,000 barrels a day previously.
"The oil plume escaping from the riser pipe has visibly declined today," BP spokesman Mark Proegler said after the company announced that a mile-long tube was tapping into the larger of two leaks from the well.
However, live video feed of the leak, provided by BP, showed a black plume of crude oil still billowing out into the deep waters.
BP has been estimating the leak was flowing at a rate of 5,000 barrels per day, but scientists and the government have questioned that figure.
Scientists analyzing video of the oil gushing from the seabed have pegged the spill's volume at about 70,000 barrels (2.9 million gallons/11 million liters) per day.
"It's just not working," U.S. Senator Barbara Boxer, who heads the Senate Environment and Public Works Committee, told CNN as she watched the BP video. The California Democrat denounced a "cover-up" of the real size of the oil spill.
U.S. Representative Edward Markey, who requested the footage, was also unimpressed.
"BP has stonewalled on releasing the video for 23 days. ... If you look at the video you can see plumes of oil spilling into the Gulf far in excess of 5,000 barrels per day," he told reporters in Washington.
Proegler and other BP spokesmen made clear the increased containment, while an advance, was not siphoning all the escaping oil. "We're not claiming that we stopped it -- although that is our final objective. We're saying that this is what we're capturing now," he said.
The U.S. government, grappling with a potentially huge environmental and economic disaster, also said Thursday it would not rely only on data provided by BP, but would make its own checks on the magnitude of the leak.
In other developments, the U.S. Environmental Protection Agency ordered BP to identify safer dispersants within 24 hours that can be used to contain the spill.
The EPA Thursday directed BP to begin using this safer dispersant within 72 hours. If BP can not identify an available alternative dispersant, the company must provide EPA and the Coast Guard with the reasons they believe no other dispersant meets required standards.
The use of dispersants, including those manufactured by Nalco Holding Co., at such high rates and at such deep levels has set off alarm bells with some environmentalists, who worry the chemicals may have a lasting negative impact.
Sheets of heavy oil came ashore in Louisiana's wetlands on Wednesday for the first time since the rig exploded a month ago. The marshes are nurseries for shrimp, oysters, crabs and fish that make Louisiana the top commercial seafood producer in the continental United States. Fishing is now banned in a large part of the Gulf waters because of the spill.
In Pass-a-Loutre, Louisiana, thick sheets of gooey brown oil swamped islands of marsh grass at the southern tip of a Mississippi River channel Thursday.
"To see the extent to which it is oiled and the depth into the island is stunning," said Maura Wood of the National Wildlife Federation's Coastal Louisiana Restoration Project.
The oil pollution covers only a fragment of the vast network of waterways, channels and islands that make up the Delta region, but environmentalists fear it is just the start.
"It's going to take a long time for us to recover from BP's mess," boat captain Richard Blink said.
(Additional reporting by Anna Driver in Houston, Richard Cowan, Jeff Mason, Tabassum Zakaria, Vicki Allen in Washington, Tom Bergin in London and Tom Brown and Pascal Fletcher in Miami; Writing by Ed Stoddard and Jane Sutton; editing by Todd Eastham)