HOUSTON, Aug 8 (Reuters) - U.S. oil refiner Citgo

Petroleum on Thursday reported a net loss of $25

million in the second quarter following less favorable market

conditions, compared with a net income of $410 million in the

previous quarter.

"Our second quarter earnings reflect a lower margin

environment and the impact of extensive turnaround and

maintenance activities at our refineries," Citgo's Chief

Executive Carlos Jorda, said in a release.