HOUSTON (Reuters) -A U.S. judge on Monday authorized a court officer overseeing an auction of shares in the parent of Venezuela-owned refiner Citgo Petroleum to receive and negotiate improved bids this week before confirming or changing the winner recommendation he made last month.

A final winner recommendation in the complex court-organized auction is expected to be submitted by the end of this month, Judge Leonard Stark said in a hearing.

(Reporting by Marianna Parraga; Editing by Chris Reese)