Ms Massi Fritz said in a text message sent to the Associated Press that "we are going to do everything" to have the Swedish case reopened "so Assange can be extradited to Sweden and prosecuted for rape".
The message, shared on Twitter, reads: "We are writing to request that you do everything you can to champion action that will ensure Julian Assange can be extradited to Sweden in the event Sweden make an extradition request".
However, lawyer Rebecca Niblock said that, if Sweden made an extradition request, it would be for the home secretary to decide which would take precedence, considering factors such as which was made first and the seriousness of the offence.
In May 2017, Sweden's top prosecutor dropped the long-running inquiry into a rape claim against Assange, which he has always denied.
Assange sought refuge in the Ecuador embassy, in Knightsbridge, west London, in 2012 to avoid extradition to Sweden over allegations of sexual assault.
"And if he's not innocent then of course the Swedish justice system is generally seen as quite fair - he won't be mistreated as we suspect he will be at a U.S. super-max jail".
THE arrest of Julian Assange by British authorities is deeply troubling.
Some Conservative Party members are also backing the move.
Assange spent nearly seven years in the Ecuadorian embassy in London, where he sought political asylum in 2012 after failing in his legal battle against extradition to Sweden, where he was wanted over two separate allegations, one of rape and one of molestation.
If the country does decide to go ahead and submit its own extradition request, it would be up to United Kingdom courts to decide on whether it should take precedence over the expected petition from the US.
A legal source familiar with the case told AFP that Assange was being held at Belmarsh prison in southeast London.
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.
Mr Marchan said: "He has said that we were spying on him, he has said we were lying, we were agents of the United States".
He was arrested Thursday after Ecuador withdrew his asylum.
After getting the boot, Assange was taken to a London court where he was found guilty of failing to surrender. He could be jailed for up to a year when he is sentenced at a later date.