(Adds PDVSA response, paragraphs 8, 9)
By Brian Ellsworth and Alexandra Ulmer
Oct 7 (Reuters) - Subsidiaries of U.S. oil company ConocoPhillips have sued Venezuelan state oil company PDVSA in Delaware, according to a court filing, accusing it of fraudulent operations involving its U.S. subsidiary Citgo.
ConocoPhillips said in an Oct. 6 filing PDVSA operations, including an ongoing bond swap that uses shares in Citgo Holding Inc as collateral, are part of an effort to prevent Conoco from collecting compensation in a dispute over a 2007 nationalization of its Venezuela holdings.
ConocoPhillips has for nearly a decade been pursuing a case against Venezuela in a World Bank tribunal to obtain billions of dollars in compensation for the 2007 takeover of its Venezuela assets by late socialist leader Hugo Chavez.
The tribunal known as ICSID in a partial ruling in 2013 said that takeover was illegal.
The U.S. company cited numerous operations involving Citgo, including an attempt to sell it in 2014, a debt offering that financed dividend payments to PDVSA, and most recently a bond swap operation that uses Citgo Holding as collateral.
"The purpose behind each of these transfers is the same: to remove assets from the United States to Venezuela and/or to encumber assets in the United States, with the intent to hinder, delay or defraud PDVSA's and Venezuela's arbitration award creditors, including ConocoPhillips," it said in the document.
ConocoPhillips says Venezuela has also sought to protect its assets from being seized in any of some 20 arbitration cases filed by companies ranging from U.S. oil giant Exxon Mobil to small Canadian mining company Crystallex.
PDVSA said in a statement on Friday that the bond swap was "perfectly legal" and that the lawsuit did not have any legal basis.
"These claims are one more instance of manipulation by ConocoPhillips," the Caracas-based company said in a statement, adding that operations would continue as planned.
A court decision will likely take several weeks, said Carlos Bellorin, petroleum analyst at IHS.
"Before taking any additional steps the tribunal has to weigh the merits of the case and if Conoco's claims are sufficiently strong," said Bellorin.
PDVSA's bonds dropped sharply on Friday after it postponed a deadline for offering to swap debt due to low participation, signaling that investor reluctance could scuttle the operation, and following news of Conoco's suit. (Editing by Phil Berlowitz, Marguerita Choy and David Gregorio)