Facebook on Monday called on a judge to toss out a New York man's claim to partial ownership of the world's leading social network on the basis that the suit is bogus.
Paul Ceglia went to court in June with a claim that he signed a contract with Facebook co-founder Mark Zuckerberg in April 2003 to design a website called "The Face Book" or "The Page Book."
Ceglia submitted a copy of a contract with Zuckerberg to the court hearing the case in Buffalo, New York.
Facebook lawyers on Monday filed a motion to have the case dismissed on the grounds that Ceglia backed his claim with "forged documents and fabricated emails."
"The evidence is in, and it is devastating for Ceglia and his cohorts," Facebook said in court documents. "This entire lawsuit is a fraud and a lie."
Facebook lawyers also accused "Ceglia and his co-conspirators" of destroying or tampering with evidence and defying court orders.
Ceglia will have time to file a legal response before a judge rules on Facebook's request for the case to be booted out of court.
Lawyers for Zuckerberg and Facebook maintain that the contract submitted by Ceglia is a doctored version of a different written agreement between Zuckerberg and Ceglia.
That contract concerns work Zuckerberg did for Ceglia in 2003 on a website called StreetFax, which provided a photo database of traffic intersections for insurance adjusters.
It makes no mention of Facebook.
"The court-ordered forensic testing has uncovered the authentic contract between Mark Zuckerberg and StreetFax that Ceglia attempted to conceal," a Facebook filing said.
"This smoking-gun evidence confirms what Defendants have said all along: the purported contract attached to the complaint is an outright fabrication."
Facebook lawyers have denounced the suit by Ceglia as a "brazen and outrageous fraud" and described him as a "hustler."
New York state Attorney General Andrew Cuomo accused Ceglia in 2009 of taking more than 200,000 dollars from customers of his wood fuel pellet company and then failing to deliver any products or refunds.
Facebook's origins have been the subject of two recent books and a hit Hollywood movie, "The Social Network."
Explore further: Facebook rejects ownership suit as a 'fraud'