NEW YORK, Aug 23 (Reuters) - BP Plc said on Thursday an alkylation unit at its 337,000 barrels-per-day refinery in Whiting, Indiana, was the source of the 50,000 barrels of gasoline it recalled earlier this week.
The company recalled the batch sold at some 200 retail outlets in northwest Indiana and Chicago areas after high levels of residue in the fuel caused problems with vehicle engines.
BP did not disclose the problem with the alkylation unit but said in a statement that the refinery has made changes to its operations to fix it.
It is also inspecting the distribution systems that carry the refined product from the refinery to nearby markets and is testing gasoline that was shipped to stations in northwest Indiana, Chicagoland and Milwaukee.
BP, which has begun paying claims, said it stopped selling premium and mid-grade gasoline in the Chicagoland until further testing is complete. On Wednesday, it said 7,000 consumers had called regarding the bad gasoline.
Indiana attorney general Greg Zoeller opened an investigation into the gasoline recall on Wednesday.
"We are closely monitoring the response by BP and will be reviewing their claims and reimbursement processes," Zoeller said in a statement. (Reporting by Selam Gebrekidan; Editing by Bob Burgdorfer)