NEW ORLEANS (AP) -- A federal agency says a remote underwater vehicle is surveying plugged undersea oil wells and looking for natural seepage as authorities seek the source of a 10-mile oil sheen in the Gulf of Mexico off Louisiana.
The Bureau of Safety and Environmental Enforcement says it has instructed operators of pipelines in the area to survey their lines.
The sheen is about 130 miles southeast of New Orleans. Royal Dutch Shell PLC has two production platforms in the area. The company said Thursday it is confident the sheen didn't originate from its operations.
The federal agency said it directed Shell to conduct a seafloor assessment using a robot vehicle. Natural seepage is known to occur in the area.
The sheen was spotted on Wednesday.