'The US attorney general, Jeff Sessions, says arresting Wikileaks founder Julian Assange is a "priority".
Mr Assange has been confined to London's Ecuadorian embassy, where he has asylum, for almost five years.
Asked about the possibility of his arrest, Mr Sessions said: "We've already begun to step up our efforts and whenever a case can be made, we will seek to put some people in jail."
Earlier reports had suggested US authorities were preparing charges.'
Read More: Julian Assange's arrest a 'priority' for US attorney general