BP says it has started to siphon oil from a leaking well in the Gulf of Mexico to a tanker on the surface.
At a news conference on Sunday, senior executive vice-president Kent Wells said so far the system was "working extremely well".
BP has used underwater robots to insert a long narrow tube with a stopper into the leaking pipe.
The BBC reports the 15cm tube could capture more than three-quarters of the leak. However, a smaller spill nearby also has to be contained.
The tool became dislodged after it was first inserted a mile beneath the surface on Saturday night.
But Mr Wells said on Sunday in Houston, Texas, that it was now back in place. He would not say how much oil was being siphoned but said the process was "working well".
Mr Wells said the company plans to slowly increase the amount of oil and gas flowing through the pipe to the tanker over the next few days.
Thousands of barrels of oil per day have been gushing from a well on the seabed since a drilling rig exploded on 20 April, 77km off the coast of Louisiana.
Last week BP tried to cap the well with a 100 tonne box, but gave up after it became encrusted with ice crystals.
Scientists from the National Institute for Undersea Science and Technology said on Sunday they had found vast underwater plumes of oil, one 10 miles (16km) long and a mile wide.
US President Barack Obama, is proposing new legislation to provide $US188 million in emergency funding, to cope with the fallout from the oil spill.
The administration intends to recover most of the money from BP.
BP says the oil spill has cost it $US450 million so far.
BP shares dropped by more than 3% in London on Friday. Their market value is down by $US30 billion since the oil rig fire.