Assange is now serving 50 weeks imprisonment sentence in UK's Belmarsh prison for skipping bail to avoid being sent to Sweden over sexual assault allegations.
Soon after his arrest in London, the U.S. sought his extradition to face charges of computer hacking and being involved in a compromise of classified information, a charge that carries a maximum sentence of five years.
A department spokesperson told The Washington Times that the USA submitted its request to the United Kingdom government for the extradition of Mr. Assange ahead of a deadline this week to do so.
A Swedish court recently ruled that Mr. Assange should not be extradited for the sexual-assault case, but investigators still want to question him in London.
The Justice Department has charged Mr. Assange in connection with material provided to WikiLeaks by former Army intelligence analyst Chelsea Manning and published online in 2010, including classified documents originating from the Departments of Defense and State. He sought refuge in the Ecuadoran embassy in London and remained there until last April, when the embassy turned him over to British police. That is because the U.S. -U.K. treaty prohibits extradition for the specific charges Assange faces.
Britain will now consider the USA extradition request and any possible new request from Sweden. It prohibits anyone from obtaining and publishing information relating to national defence, or inducing someone to hand over information.
Assange, 47, faces up to ten years in prison for each of the new charges.
USA authorities allege the whistleblower conspired with Manning, 31, "with reason to believe that the information was to be used to the injury of the United States or the advantage of a foreign nation". "Some say that Assange is a journalist and that he should be immune from prosecution for these actions", John Demers, the Assistant Attorney-General for National Security, said when the indictment was filed last month.
"It can't be overstated how important this case is for press freedom", Mr. Hrafnsson said.
"It's an indication of the watershed moment that we are now seeing in the attack on journalism", he said.
But a Swedish judge shot down the chances of his being extradited to that country, rejecting a request in early June to issue an arrest order.
Just a few hours before that hearing, WikiLeaks said it had "grave concerns about the state of health of our publisher, Julian Assange, who has been moved to the health ward of Belmarsh prison".