The lawyer representing the US said Washington had computer room chats proving that Assange had been involved in real-time discussions with Chelsea Manning, a former US Army intelligence analyst who has already been jailed for leaking hundreds of thousands of documents to WikiLeaks in 2010.
Assange was sentenced to 50 weeks in prison on Wednesday for skipping his bail in June 2012, when he took refuge in the Ecuadorian embassy.
The bail was related to a case in Sweden accusing him of rape and sexual assault on two women. The case was later dropped although Assange remained in the embassy fearing he would be ultimately transferred to the US.
The British court investigating Assange’s extradition case said its next session will come on May 30 and June 12. Judge Michael Snow told the court that a full extradition hearing will be held months later.