HOUSTON (Reuters) -Oil refiner Citgo Petroleum on Thursday reported its first quarter net fell 56% to $410 million, from $937 million in the same period a year ago.

The Venezuela owned company said it throughput rose to 830,000 barrels per day, the third highest in its history, up from 814,000 bpd in the year-ago quarter.

"We achieved these results with turnaround activities underway at two refineries while successfully restarting two offline units that we believe will further enhance our crude processing capabilities," CEO Carlos Jorda said in a statement.

The seventh-largest U.S. refiner is in the midst of a Delaware court's auction of shares in parent PDV Holding, whose only asset is Citgo, that could force a change in Citgo's ownership.

The auction is to repay billions of dollars in claims for debt defaults and expropriations against Venezuela. Bids in the second-round of the court auction are due June 11.

Citgo's crude utilization rate, or how much oil its three plants were able to process compared with full capacity, was 95% last quarter despite the turnarounds, compared to 96% in the first quarter a year ago, the company said.