Julian Assange's arrest is a "priority" for United States authorities, America's attorney general has said.
Prosecutors are believed to be preparing or considering charges against WikiLeaks and its founder, according to US media reports.
WikiLeaks has a reputation for publicly posting leaked information on US government activities.
Last month WikiLeaks released nearly 8,000 documents that it says reveal secrets about the CIA's cyber-espionage tools for breaking into computers, mobile phones and even smart TVs.
Mr Assange has not left Ecuador's embassy, tucked behind Harrods in London's Knightsbridge, since he walked through the door seeking political asylum in June 2012.
He is wanted in Sweden over a sex allegation dating back to 2010, but he fears he will be extradited to the US for questioning over the activities of WikiLeaks if he complies with Swedish authorities.
US attorney general Jeff Sessions was asked in a press conference whether it was a priority for him to arrest Mr Assange.
He said: "We are going to step up our effort and already are stepping up our efforts on all leaks.
"This is a matter that's gone beyond anything I'm aware of. We have professionals that have been in the security business of the United States for many years that are shocked by the number of leaks and some of them are quite serious.
"So yes, it is a priority. 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."
According to CNN, authorities are preparing to seek his arrest.
But Mr Assange's lawyer, Barry Pollack, said he had not been made aware of any developments.
He added: "The Department of Justice should not be treating the publication of truthful information as a reason for a criminal investigation of the publisher.
"Democracy has always depended on journalists being able to inform the public of what their government is doing."
When approached by the Press Association, the US Department of Justice declined to comment on the reports.