Coast Guard says to set leaking oil ablaze

Response boats work to clean up oil where the Deepwater Horizon oil rig sank, off Louisiana in this April 22, 2010 handout photo.

Credit: Reuters/U.S. Coast Guard/Handout

HOUSTON (Reuters) - The Coast Guard said it will start a "controlled burn" on Wednesday to battle a giant oil slick from last week's deadly offshore drilling rig explosion, as the spill threatened wide-scale coastal damage for four U.S. Gulf Coast states.

The leaking well, 5,000 feet under the ocean surface off Louisiana's coast, has created an oil sheen and emulsified crude slick with a circumference of about 600 miles, covering about 28,600 square miles (74,070 sq. km), the Coast Guard said on Tuesday. That's slightly bigger than the state of West Virginia.

Swiss-based Transocean Ltd's Deepwater Horizon rig sank on April 22, two days after it exploded and caught fire while finishing a well for BP Plc about 40 miles southeast of the mouth of the Mississippi River.

Eleven workers from the rig are missing and presumed dead in what is the worst oil rig disaster in almost a decade.