Earlier Friday a Coast Guard official said that oil was not spilling from the deep-water well off the coast of Louisiana, apparently easing concerns of a potential environmental disaster days after the explosion left a one-by-five-mile sheen of oil on the Gulf of Mexico.

“It does not appear that oil is emanating from the hole,” said Katherine McNamara, a fireman with the Coast Guard.

Ms. McNamara said the assessment was made by using a remote-controlled device equipped with a camera and sonar. Officials with the Coast Guard and BP, the company leasing the rig, said they were still trying to determine why oil was not escaping from the well, and whether that remains a possibility.

Image Smoke and a trail of oil were already causing concern on Wednesday, a day before the rig sank into the Gulf of Mexico.

David Rainey, a vice president for Gulf of Mexico exploration for BP, said Thursday: “If there is any other oil that’s coming from the well, it would be coming from the subsurface, so it would be coming from below the seabed. The well was just over 18,000 feet deep, and we don’t know from where in that 18,000 feet it would be coming.”