The 47-year-old – who was evicted on April 11 from the Ecuadorian Embassy in London, where he had been holed up since 2012 after Ecuador granted him political asylum – is the subject of a recent extradition request submitted by the U.S. government, a U.S. official who spoke on condition of anonymity told the Associated Press.
Assange faces an 18-count indictment that accuses him of soliciting and publishing classified information and of conspiring with former Army private Chelsea Manning to crack a Defense Department computer password.
That indictment, which includes Espionage Act charges, was issued by the Justice Department last month and is pending in federal court in Alexandria, Virginia.
Sweden also seeks him for questioning about an alleged rape, which Assange has denied.
Assange was arrested by British police following his eviction in April and is currently serving a 50-week sentence for jumping bail.
WikiLeaks, the anti-secrecy organization which Assange founded and for which he published multiple secret U.S. military cables regarding the Iraq and Afghanistan wars, previously has condemned the Ecuadorean and British governments for taking him into custody.
"This man is a son, a father, a brother. He has won dozens of journalism awards. He's been nominated for the Nobel Peace Prize every year since 2010," it said in a tweet in April. "Powerful actors, including CIA, are engaged in a sophisticated effort to dehumanize, delegitimize and imprison him."
Edward Snowden, who infamously leaked highly classified NSA information, tweeted Assange's arrest was "going to end up in the history books."
British Foreign Secretary Jeremy Hunt thanked the Ecuadorean government for their cooperation with the Assange arrest, while Prime Minister Theresa May said it proved that "no one is above the law."
The extradition request had been expected ever since U.S. authorities first announced a criminal case against Assange.
Last month though, he told a British court that he would refuse to be sent to the U.S.
The WikiLeaks founder, addressing the court via video link from a prison in London, said he won’t “surrender myself for extradition for doing journalism that has won many awards and protected many people.”
Fox News’ Ryan Gaydos, Lukas Mikelionis and the Associated Press contributed to this report.