BP saw the first significant progress in its seven-week attempt to capture oil pouring from its leaking well in the Gulf of Mexico on Sunday, but was still catching only about half of the estimated flow.
Tony Hayward, chief executive, said he hoped the cap lowered over the well last week would eventually catch the “vast majority” of the leaking oil. But US authorities warned that there was a “long way to go” before it reached that point.
The company is working to increase the efficiency of its containment cap, fitted to the top of broken valves on the seabed in 5,000ft of water.
On Saturday, the cap collected about 10,500 barrels of oil. The estimated flow from the well has been put at 12,000-19,000 barrels per day.
The system has a limit of 15,000bpd on the volume it can handle, which is restricted by the capacity on the Discoverer Enterprise ship collecting the oil on the surface.
BP is attempting to put in place an additional containment system, using the pipes from the failed “top kill” attempt to plug the well.
The pipes are connected to the failed blow-out preventer – the stack of valves on the seabed intended to prevent escapes of oil and gas – and can be used to allow more oil to be captured by another vessel on the surface.
Mr Hayward told BBC television on Sunday that the group hoped to have the additional system operational by next weekend.
“When those two [systems] are in place, we would very much hope to be containing the vast majority of the oil,” he said.
Thad Allen, the US Coast Guard admiral in charge of the federal response, told Fox News Sunday that BP was slowly raising production from the containment cap but warned that “we have a way to go to catch what we think the rate of flow is”.
On ABC News, Adm Allen described the clean-up as “an insidious war, because [the spill is] attacking, you know, four states one at a time, and it comes from different directions depending on the weather”.
The extent of the spill and its dispersed nature has stretched coast guard resources.
“It’s disaggregated itself into hundreds, maybe thousands of smaller pieces of oil. So we’re trying to fight it on a lot of different fronts,” Adm Allen said.
Mr Hayward reiterated his promise to keep paying all compensation claims presented by fishermen and others hurt by the spill.
“We have the financial strength to see through this and we have the determination to do the right thing, to rebuild our reputation,” he said.