HOUSTON, June 11 (Reuters) - A U.S. federal court is

accepting binding offers through Tuesday for shares in the

parent of Venezuela-owned refiner Citgo Petroleum, a crucial

step in a long-running case where 18 creditors are seeking up to

$21.3 billion for past expropriations and debt defaults.

The share auction, organized in Delaware to pay creditors

including oil producer ConocoPhillips ( COP ) and miners Rusoro

, Crystallex and Gold Reserve ( GDRZF ), has attracted

investors and firms with substantial resources, boosting the

chances of an ownership change for the seventh-largest U.S.

refiner.

Hedge fund Elliott Investment Management has been weighing a

bid, while a group of creditors represented by Centerview

Partners aims to lure Conoco to join another offer for Citgo

parent PDV Holding, sources told Reuters in April.

Citgo is the largest asset targeted by creditors trying to

get compensation for late President Hugo Chavez'

nationalizations two decades ago and President Nicolas Maduro's

failed debt payments.

Maduro has rejected the auction and said Washington is

trying to steal Venezuela's foreign assets. But his government

has made little effort to honor the country's debts.

A court officer specially appointed for the case and

investment bank Evercore Group are in charge of receiving and

analyzing the bids. The deadline to complete the sales process,

including awarding the round's winners, is July 15.

Citgo Petroleum, controlled by supervising boards since it

severed ties in 2019 with its ultimate parent, Caracas-based

state oil company PDVSA, is the crown jewel of Venezuela's

foreign assets, processing up to 807,000 barrels of oil per day.

In the last two years, the company has generated $4.8

billion in combined net earnings.

Parties representing Venezuela in Delaware are hopeful that

offers in this second bidding round will be higher than

non-binding bids in the first round in January, which only

reached $7.3 billion, compared with Citgo's valuation of $11

billion to $13 billion.

Venezuela might press the court for a third bidding round if

offers do not approach $10 billion, two sources said on Monday.

As the bidding deadline approached, politicians and envoys

representing Venezuela began doubling down on efforts to halt

the auction. This month, they asked the White House and U.S.

Congress to pause the court process until a presidential

election is completed in Venezuela in July.

The boards supervising Citgo also continue trying to reach

payment agreements with some creditors, including Conoco and the

holders of PDVSA's 2020 bonds, which are collateralized with

another Citgo parent's equity.

Among the highest-ranked creditors that stand to collect

proceeds from the auction are shipbuilder Huntington Ingalls

Industries ( HII ), marine services firm Tidewater,

conglomerate Koch Industries and glass container manufacturer

O-I Glass ( OI ).