US prosecutors have just under two months to present British authorities with a final and detailed criminal case to justify Julian Assange's possible extradition, a US government official says.
The official, who wished to remain anonymous, says US authorities have already sent Britain a provisional arrest warrant regarding Assange's extradition.
But within 60 days from Thursday, when British police bundled Assange out of the Ecuadorian embassy in London, US authorities must submit a formal request outlining all the legal charges Assange would face if he is transferred into US custody.
According to a criminal indictment that was only unsealed after the WikiLeaks founder's arrest, Assange is charged with conspiring with former army intelligence analyst Chelsea Manning to gain unauthorised access to a government computer.
The US indictment filed in March 2018 said Assange in March 2010 engaged in a conspiracy to help Manning crack a password stored on Defense Department computers connected to the Secret Internet Protocol Network (SIPRNet), a US government network used for classified documents and communications.
Assange's contacts with Manning led to one of the biggest ever leaks of classified information as WikiLeaks published hundreds of thousands of US military reports and diplomatic communications.
The US official said that within the 60-day period, US authorities could modify or add to the current charges they have filed against Assange.
The official declined to say whether further charges were likely, but legal experts have said they are certainly possible.
A witness who prosecutors were seeking to interview and an associate of Assange based in Europe - who also requested anonymity - said that before his arrest Assange worried that US prosecutors would also bring charges related to WikiLeaks' publication of CIA computer hacking tools, which the website described as its "Vault 7" cache.
US officials have said that the disclosure of details about the US spy agency's abilities to perform electronic surveillance and cyber warfare was potentially far more damaging to government activities than anything Manning made available to WikiLeaks.
In a Friday interview with CNN, US Vice President Mike Pence said the United States was "going to bring Julian Assange to justice".
Pence denied that statements by President Donald Trump, in which he praised WikiLeaks during the 2016 US election campaign, were in any way an endorsement of the organisation.