During the 2016 US presidential campaign, Wikileaks published a series of Democratic National Committee emails damaging to Democratic candidate Hillary Clinton.
"Julian needs to be released now. For him, for our family, and for the society we all want our children to grow up in."
"We are talking about collateral murder, evidence of war crimes," she said. "They are a remarkable resource for those of us seeking to hold governments to account for abuses."
A hero to admirers who say he has exposed abuses of power, Wikileaks founder Julian Assange is cast by critics as a dangerous enemy of the state who has undermined Western security.
Assange appeared by videolink from prison as lawyers discussed the management of his hearing next week to decide whether he should be extradited to the United States.
A CIA spokeswoman declined to comment.
The request was reportedly made last Thursday, but only became known to the public on Monday.
Assange is being held in the high-security Belmarsh prison "as if he were convicted for a serious criminal offense."
"Julian Assange, 47, has today, Thursday 11 April, been arrested by officers from the Metropolitan Police Service (MPS) at the Embassy of Ecuador," police said.
In a statement, Ecuador's foreign ministry denied it had reached an agreement with the British government to jail Assange if he left the embassy.