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CARACAS, Oct 17 (Reuters) - Venezuelan state oil company PDVSA is to extend the second deadline for a $5.3 billion bond swap offer to Friday and says if unsuccessful, it “could be difficult” to pay existing debt.

The cash-strapped company has already extended the deadline twice and said it received "substantially less" offers than a key requirement of needing more than 50 percent participation to go through. (goo.gl/o6jJlr)

“If the Exchange Offers are not successful, it could be difficult for the Company to make scheduled payments on its existing debt ... which would result in the Company evaluating all alternative options,” PDVSA said in a statement.

The company added that low oil prices would “impair” its “ability to make scheduled payments on its existing debt.”

President Nicolas Maduro has long insisted that Venezuela and PDVSA would honor all debt payments and has harshly criticized as politically motivated any talk of default.

Sources told Reuters that central bank president Nelson Merentes recently reiterated Venezuela’s willingness to pay in a rare private meeting with investors in Washington.

The swap allows investors to exchange bonds maturing in 2017 for a new bond set to mature in 2020, backed by shares in U.S. subsidiary Citgo Holdings Inc.

Both the early tender deadline and the expiration date were extended to Friday at 5 p.m. EDT (2100 GMT).

Bond prices fell on Thursday after the second deadline extension.

Venezuela is undergoing a major economic crisis, with many people struggling for food and medicines. Annual inflation is in triple digits.

Maduro blames the problems on an “economic war” being waged against his government.

On Friday, PDVSA President Eulogio Del Pino filed a lawsuit against a Venezuelan newspaper, accusing it of defamation and attempting to harm the bond swap after it published an article saying the company was in financial trouble. (Reporting by Girish Gupta and Corina Pons; Editing by Sandra Maler and Leslie Adler)