BP has capped and plugged an abandoned piece of equipment believed to be the source of a sheen spotted near the site of its massive 2010 oil spill in the Gulf of Mexico.
The London-based oil giant said it placed a 750lb cap over an 86-ton steel container that the company had deployed in a failed effort to contain the spill.
BP also inserted plugs on the top and sides of the container, which had been lowered over a leaking drill pipe in an effort to funnel oil to the surface.
BP and the US Coast Guard say no oil has been seen leaking out of the container since it was capped and plugged. The operation started on Tuesday and lasted about 26 hours.
The sheen appeared on the Gulf's surface in September. BP plans to monitor the sheen by satellite for several more days.
The coastguard says it has directed BP to submit a plan for either removing remaining oil from the container or removing the container itself after the oil is removed.
US congressman Edward Markey, who serves on the House of Representatives' Natural Resources Committee, said oil should be removed from the container along with any wreckage that was left behind on the seabed. He is also asking BP to publicly release all video footage its remotely-operated vehicles have shot recently near the well. "We shouldn't have to wait for the next leak to plug another problem," Mr Markey said.
Last week BP said a three-day inspection confirmed that its Macondo well, which blew out and led to the nation's worst offshore oil spill, isn't leaking.
Before the container was capped, the coastguard said underwater video showed apparent oil globules leaking from the dome at an estimated rate of less than 100 gallons a day. The container sits on the seabed, about 1,500 feet from the wellhead. The coastguard has said the sheen is not feasible to recover and does not pose a risk to the shoreline.
Eleven workers were killed when the blowout triggered a deadly explosion on the Deepwater Horizon drilling rig, owned by Transocean Ltd, and leased by BP. Millions of gallons of oil spewed into the Gulf before BP sealed the well.