BP sharply reduced its estimate on Monday of how much oil it is siphoning off each day from a ruptured well in the Gulf of Mexico that has been spewing oil for a month and threatening ecological disaster.

The British-based energy giant said the oil captured on average by a mile-long siphon tube was 2,010 barrels (84,420 gallons/319,500 litres) per day in the six days before May 23, less than half the up to 5,000 barrels (210,000 gallons/795,000 litres) per day the company estimated it had been capturing.

At times the capture was as low as 1,360 barrels per day (57,120 gallons/216,200 litres).

The oil group believes about 5,000 barrels have been leaking every day, although some experts have given significantly higher estimates for the size of the leak.

The lower estimate came as two members of U.S. President Barack Obama’s Cabinet were to visit the fouled Gulf Coast on Monday to keep pressure on BP in hopes of averting a looming environmental catastrophe.

The Obama administration warned the company on Sunday that it would be removed from efforts to seal the well if it is not seen as doing enough. But it acknowledged that only the company and the oil industry have the know-how to stop the leak.

BP is readying new measures to try to stop the gushing torrent of oil that began after an April 20 explosion sank the Deepwater Horizon rig, killing 11 workers.

BP shares have taken a beating in the markets since the accident. On Monday its share price fell 1.9 pct, with sentiment hit by renewed pressure from the Obama administration.

But today’s news on the bill and the amount of oil the company is siphoning off remains within existing estimates. The market looks squarely focused on BP’s effort in the next few days to plug the well completely.

“We had the initial euphoria on Thursday that it was doing 5,000 (barrels) and then they revised down the numbers and there was a bit of concern about exactly how much crude was coming out. I think the market was very much aware of this one,” said Panmure Gordon analyst Peter Hitchens.

“Really what everyone’s waiting for is the top kill operation which should be coming up in the next couple of days hopefully. Touch wood. That really is the key: whether they can actually kill off this well.”

“We very much got a bad reaction on Friday. This is just confirmation that they’re getting some of it out but not all of it so really it’s down to this top kill.”

MARRING MARSHLANDS

Oil has been sloshing into Louisiana’s fragile marshlands and over 65 miles (110 kms) of shoreline have been tarred.

Interior Secretary Ken Salazar and Homeland Security Secretary Janet Napolitano, accompanied by a U.S. Senate delegation, were due to visit the state on Monday and fly over the affected areas.

They also will discuss the latest response efforts with federal officials and BP representatives, and meet with Louisiana Governor Bobby Jindal and local community and industry leaders, the departments of Interior and Homeland Security said in a statement.

Salazar said on Sunday Washington was frustrated and angry that BP has missed “deadline after deadline” in its efforts to seal the well more than a month after an oil rig explosion triggered the disaster.

“If we find they’re not doing what they’re supposed to be doing, we’ll push them out of the way appropriately,” he said after visiting BP’s U.S. headquarters in Houston.

(Additional reporting by Sarah Young; Writing by Ed Stoddard and Doina Chiacu; Editing by Matthew Jones)