HOUSTON (Reuters) - Key terms of a proposed court agreement with a U.S. hedge fund seeking to gain control of oil refiner Citgo Petroleum from Venezuela would lock in the fund's low-ball bid, the company's creditors said in new court filings against the deal.

The backlash to Elliott Investment Management's wholly-owned Amber Energy's offer ends any chance this year of a change to Citgo's ownership to satisfy debt defaults and expropriations by Venezuela.

The offer is not economically viable, deficient, and does not comply with Delaware law, creditors, who are seeking cash proceeds from a court auction, wrote in asking the court to begin anew.

Amber, which a court officer had hailed last month as the "successful bidder" in the auction's second round, threatened to walk away if the court approved creditors' requests for more details of its up to $7.286 billion bid to assemble rival bids. Citgo called Amber a "weeks-old shell corporation with no assets and no committed financing," in its court filing.

Terms of a sales agreement put together by a court officer overseeing the auction unduly favor Elliott's Amber and violate the court's rules governing the sale, creditors wrote in filings late on Friday that went beyond their earlier criticisms.

The judge in the case asked the court officer to poll creditors on their view of the offer.

Crystallex, the company that brought the lawsuit which found Citgo's parent PDV Holding liable for Venezuela's debts, described the auction as having "gone severely off course."

REOPEN DATA ROOM

It and ConocoPhillips ( COP ), which holds the largest claims in the case, asked that Citgo financial information be made available immediately to other bidders. Access has been closed since August, when Elliott was chosen to exclusively negotiate a deal.

Gold Reserve ( GDRZF ), a mining firm holding a $1 billion claim against Venezuela, said it was prepared to finalize "a materially superior" bid once it could review Citgo data.

Robert Pincus, the court officer overseeing the auction, said in a filing he opposes reopening the Citgo financial data until Dec. 9, and wants the judge in the case to restrict information on Amber's financial terms and to approve a breakup fee if a superior bid is accepted. The size of the potential fee was redacted in court filings.

Pincus proposed a revised sale schedule that would allow him to submit a final recommendation in late January, and give the court until March 24 to begin a hearing on a definitive sale.

He disagreed with creditors' criticisms of the sales process, their descriptions of the proposed Elliott agreement, and offered to provide his own views in a future court hearing, Pincus wrote.