Gasoline prices in the Chicago-area climbed by at least 20 cents a gallon in the days following the Feb. 1 power outage at the Whiting plant, the largest refinery in the U.S. Midwest.

"The Whiting Refinery is back to normal operations," company spokesperson Christina Audisho said in a emailed statement.

Reuters reported in February that BP planned to begin preparing the Whiting refinery for restart late that month and would carry the restart out in the first part of March.

(Reporting by Erwin Seba; Editing by Marguerita Choy)

By Erwin Seba