On the second day of his extradition hearing in a London court, lawyers for Assange attacked Sweden's attempts to extradite him from Britain, saying prosecutors had failed to follow correct procedure.
The hearing, initially scheduled to last two days, will now reconvene on Friday when lawyers will make closing statements, although the judge in the case is not expected to give his decision until later this month.
Assange was arrested in Britain in December on an international warrant issued by Sweden.
Swedish prosecutor Marianne Ny wants to question Assange over allegations of sexual assault made by two women he met during a seminar organised by the whistleblowing website in August last year.
Assange denies the allegations made by the two women and insists they are politically motivated, stemming from WikiLeaks' release of thousands of classified US cables which has enraged Washington.
The 39-year-old Australian is afraid that extradition to Sweden will lead to him eventually being delivered to the United States, where some politicians have called for him to face the death penalty for leaking state secrets.
Assange's Swedish lawyer told the packed courtroom on Tuesday that it was "wrong" for Ny to claim it had been impossible to contact his client.
Björn Hurtig said he had contacted the prosecutor on five occasions in September and October "and offered that Julian could be interrogated in Sweden -- I would even say I requested it".
He said he later proposed that Ny could interview Assange by other means, such as by video-link, or that police in Britain be allowed to interview him.
"But she said no to everything," Hurtig said.
Sven-Erik Alhem, a former Swedish prosecutor who gave evidence for the WikiLeaks founder, accused Swedish prosecutors of failing to follow "proper procedure" while investigating the rape claims.
It was "quite peculiar" that authorities failed to get Assange's version of events before seeking his arrest, he claimed.
After Tuesday's evidence at Belmarsh Magistrates Court, Assange's lawyer in Britain pleaded with Swedish prosecutor Ny to come to court in London on Friday and argue her case.
"We have seen a prosecutor who has been ready to feed the media with information but has been unprepared to come here and subject herself to the cross-examination she knows she cannot withstand," Mark Stephens told reporters.
Sweden's prime minister took issue with the description of his country's judiciary system presented by Assange's lawyers.
Fredrik Reinfeldt said accusations by Assange's lawyers that his human rights would be violated if he stood trial for rape in Sweden were "the kind of thing you hear when (a lawyer) trying to defend a client gives a condescending description of other countries' legal systems.
"But everyone living in Sweden knows that is not in line with the truth," he told reporters in Stockholm.