Adds background on legal dispute, details of auction, comment by U.S. Treasury spokesperson, paragraphs 2-7

By Marianna Parraga

HOUSTON, Jan 13 (Reuters) - Parties representing Venezuela in a court-ordered auction of the parent of Venezuela-owned Citgo Petroleum have requested a U.S. court of appeals to vacate a ruling by a judge that ordered the sale of the shares to an affiliate of Elliott Investment Management, the board that supervises the refiner said on Tuesday.

Between late November and early December, Delaware Judge Leonard Stark approved a $5.9 billion bid from Elliott's affiliate Amber Energy for Citgo's parent, PDV Holding, following two years of bidding rounds in a sale organized to pay up to $19 billion to creditors for debt defaults and expropriations in Venezuela.

The sale order has triggered opposition from rival bidders and parties representing Venezuela, its state-owned oil company PDVSA and subsidiaries PDV Holding and Citgo Petroleum, which resorted to the U.S. Court of Appeals of the Third Circuit. The court has not made a decision.

The sale is pending execution until the U.S. Treasury Department greenlights the transaction. The Treasury's Office of Foreign Assets Control was expected to submit an opinion on the case last week before the court of appeals, but it has not.

A Treasury spokesman declined to comment on specific action, and said the department was "fully committed to supporting President Trump's efforts on behalf of the people of Venezuela."

As U.S. President Donald Trump moves quickly to put together a $100 billion effort to revive Venezuela's oil industry after capturing President Nicolas Maduro, Washington has yet to finalize the fate of Citgo, the crown jewel of the country's foreign assets, as conflicting parties increase lobbying efforts to influence the U.S. course of action.

The Venezuelan parties had introduced a motion to disqualify Amber's bid over alleged conflict of interest, which was dismissed in Delaware.

The board supervising Citgo said in a release on Tuesday that the auction was tainted by conflicts of interest and legal errors, which undermined the neutrality required in the process and reduced Citgo's value.

The board will continue to exercise defenses to protect the company, it added in the release.

(Reporting by Marianna Parraga in Houston; Editing by Julia Symmes-Cobb and Matthew Lewis)

((marianna.parraga@thomsonreuters.com; +1 713 371 7559; Reuters Messaging: @mariannaparraga))