The owner of an oil rig that caught fire following an explosion in the Gulf of Mexico last week says it has expanded its search for a missing worker.

Black Elk Energy says three dive boats are now working, and Plaquemines Parish sheriff's deputies are checking beaches.

In a statement emailed Sunday evening, the company said that all helicopter companies flying in the area have also been asked to keep an eye out, and that a search-and-rescue dog will be brought to the platform Monday.

Searchers recovered the body of a second missing worker on Saturday.

Doctors said Sunday that the condition of one of four men burned in the fire has improved to fair. Two remain in critical condition and one in serious condition.