By Matthew Bigg
VENICE, Louisiana (Reuters) - The U.S. government will independently verify how much oil has leaked into the Gulf of Mexico from a ruptured undersea well owned by BP <:BP.LO:> Interior Secretary Ken Salazar said on Thursday.
"We're not depending on what BP is telling us," Salazar said on CNN in one of a series of television appearances to address the ecological disaster unfolding in the Gulf Coast.
Energy giant BP Plc was responsible for damages so getting accurate data was essential, he said. "It's a grave and a very serious situation and we're taking nothing for granted," Salazar told NBC's "Today" show.
BP has scrambled to contain crude from the gushing seabed Macondo well since it blew out after an April 20 explosion on the Deepwater Horizon rig that killed 11 workers.
The company said it is now siphoning about 3,000 barrels (126,000 gallons/477,000 liters) a day of oil, from what it has estimated was a 5,000 barrels (210,000 gallons/795,000 liters) a day gusher.
With heavy oil washing ashore in fragile Louisiana wetlands, wildlife and environmental groups accused BP of holding back information on the real size and impact of the growing slick, and urged President Barack Obama to order a more direct federal government role in the spill response.
Salazar said the Obama administration had been aggressive in its response to the spill but had inherited a regulatory system "that essentially was rubber-stamping whatever it was the oil and gas industry wanted."
'WE KNOW MORE IS COMING'
Heavy oil -- not just tar balls -- came ashore in Louisiana for the first time since the rig exploded a month ago, threatening the state's prized marshlands. Louisiana Governor Bobby Jindal called it a "day that we have all been fearing."
"It's already here but we know more is coming," he said.
The marshes are nurseries for shrimp, oysters, crabs and fish that make Louisiana the leading producer of commercial seafood in the continental United States. Fishing is banned in a large part of the Gulf waters because of the spill.
BP said it could begin injecting mud into the well as early as Sunday in a bid to permanently plug the leak. Its shares gained more than 2 percent on Thursday in London trading.
Adding another name to the group of companies connected to the doomed rig, Schlumberger Ltd said it had a crew on the Deepwater Horizon that departed only hours before the explosion and fire that engulfed it.
The world's largest oilfield services company had not previously revealed its work on the Horizon.
In London, Greenpeace protesters scaled a balcony at BP's headquarters and hoisted a large flag bearing an oil-soaked version of the company's bright green logo and the words "British Polluters." Chief Executive Tony Hayward was expected to meet with board members on Thursday to discuss the spill.
The discovery of heavy oil in the Louisiana marshlands showed that authorities lack the capacity to track undersea oil effectively, marine conservation biologist Rick Steiner said.
It also called into question a containment effort that focused on oil on the surface of the Gulf, Steiner said.
"I am very confident that a lot of the oil that has come out has not surfaced yet and the government can't track subsurface plumes," said Steiner, a retired professor at the University of Alaska who has spent a week on the Gulf coast.
Meanwhile, the U.S. government's weather forecaster said a small portion of light sheen from the giant oil slick had entered the powerful ocean flow known as the Loop Current, which could carry the oil down to the Florida Keys, Cuba and up the U.S. East Coast.
Fallout in Washington increased. The U.S. Interior Department said its embattled Minerals Management Service will be broken up into three separate divisions in a restructuring of how it handles offshore energy production.
Top U.S. Senate Democrats urged Obama to order immediate inspections of all offshore oil rigs and production platforms.
"Until we can ensure the safety of our offshore platforms, our nation's coastlines will be threatened by the possibility of more manmade catastrophes," they said in a letter. (Additional reporting by Jeff Mason, Tabassum Zakaria and Vicki Allen; Writing by Jane Sutton; Editing by Doina Chiacu)