July 5 (Bloomberg) -- ConocoPhillips, the second-largest U.S. refiner, reported a malfunction at its refinery in Borger, Texas, causing the flaring of about 500 pounds of sulfur dioxide, according to a report on a state-administered Web site.

The flaring took place at 2:50 p.m. local time on July 3, the report on the Texas Commission of Environmental Quality Web site said.

ConocoPhillips said in May it would shut a fluid catalytic cracker and boiler for maintenance and began restarting the unit on June 29. Fluid catalytic crackers play a central role in gasoline production. The Borger plant, which can process 146,000 barrels of oil a day, is located about 50 miles (80 kilometers) north of Amarillo, Texas.

To contact the reporter on this story: Bill Murray in London at wmurray1@bloomberg.net

Last Updated: July 5, 2007 03:37 EDT