HOUSTON (Reuters) - ConocoPhillips ( COP ) has filed a court motion to preserve the U.S. oil producer's almost top priority among Citgo Petroleum creditors to cash proceeds from an auction of shares in the parent of the Venezuela-owned company.

Citgo is the only asset of PDV Holding, which a U.S. district court in Delaware has found to be liable for Venezuela's foreign debts.

Conoco's filing in the court follows lawsuits in Texas and New York by holders of Venezuelan bonds and notes trying to jump the line of creditors. Eighteen creditors aim to recover as much as $21.3 billion from the auction set to pay for expropriations and debt defaults by Venezuela.

The auction is expected to be completed in coming months.

"This action seeks to obtain writs of attachment against the shares of Citgo Holding in favor of every additional judgment creditor in the order of priority previously established by the court," Conoco said in its motion filed this week.

A spokesperson for Conoco declined to comment.

Citgo in 2019 severed ties with its ultimate parent, Caracas-based state company PDVSA, but they have U.S. subsidiaries, including Citgo Holding and PDV Holding.

A conditional bid of up to $7.3 billion selected by a court officer last month would only cover a small fraction of the claims if approved by the judge.

Conoco has three separate arbitration claims approved by Delaware to be compensated from the auction's proceeds. One of the claims, for $1.33 billion, is third in the priority order.

Conoco has in recent months also moved to seize payments to Venezuela from an offshore natural gas project being developed by PDVSA, Shell and the National Gas Company of Trinidad and Tobago.

Conoco was recently granted a license from the U.S. Treasury Department to seek the payments, Bloomberg reported earlier this month. Conoco and the Treasury Department have not confirmed the authorization.

"The risk that the ... defendants might attempt to obtain writs of attachment against the Citgo Holding shares on the basis of an alter ego theory is real," Conoco added in its motion.

"These parties have commenced actions seeking to establish that PDV Holding is the alter ego of PDVSA or the Republic in an effort to defeat this court's (property distribution)."