Swedish prosecutor Ingrid Isgren, due to be present while Assange faced a grilling by an Ecuadoran prosecutor, entered the embassy shortly before 1000 GMT, an AFP photographer reported.
Elisabeth Fritz, the lawyer for Assange’s victim, said: “My client has been waiting six years for justice… It is time for this to go to trial.”
On the other hand, Assange’s lawyer Per Samuelsson said the questioning is expected to last several days at the embassy where the founder of the secret-spilling website has been holed up for four years, refusing to come out over fears he could be extradited to the United States.
“I am very hopeful,” Samuelsson told Sweden’s TT news agency. “Objectively, there is no doubt that everything happened as Assange said it did.”
Assange, a 45-year-old Australian, sought refuge in the embassy in June 2012 after Sweden sought his arrest over allegations of rape and sexual assault. He has always denied the claims, saying they were politically motivated.
The former computer hacker insists his sexual encounters with the two women, who he met on a 2010 trip to Sweden, were consensual.
He has refused to travel to Sweden for questioning, fearing he could be extradited over WikiLeaks’ explosive release of 500,000 US secret military files on the wars in Afghanistan and Iraq.
Swedish prosecutors dropped the sexual assault probe last year after the five-year statute of limitations expired.
But they still want to question him about the 2010 rape allegation, which carries a 10-year statute of limitations.
Assange’s lawyer said he had made “repeated requests” for an interview with police to address the rape claim, though Ecuadoran prosecutors say a hearing scheduled for October was postponed at the Australian’s request.
“Julian Assange has always wanted to tell his version to the Swedish police. He wants a chance to clear his name,” Samuelsson told AFP.
The grilling comes after WikiLeaks returned to the spotlight with the leak of tens of thousands of emails from the US Democratic Party and presidential candidate Hillary Clinton’s campaign in the final weeks of the race for the White House.
Assange defended the publication, denying links with Russia and claims that his website was trying to influence the US vote which saw Trump defeat Clinton in a stunning upset.
Tensions with his Ecuadoran hosts have been growing, with the Clinton leaks prompting the embassy to cut Assange’s internet access, citing respect for “non-intervention” in the affairs of other states.