The Australian former hacker, who has vehemently denied the 2010 allegations and insisted the two sexual encounters were consensual, has been ensconced in Ecuador's embassy in London since 2012 to avoid extradition to Sweden.
Sweden's director of public prosecution Marianne Ny "has submitted a request for legal assistance to the English authorities and a request to Ecuadorian authorities regarding permission to interview Julian Assange at Ecuador's embassy in London during June-July 2015," a statement from her office said.
The questioning will, "when all necessary permits and arrangements are ready", be conducted by the supporting prosecutor in the case, chief prosecutor Ingrid Isgren, together with a police investigator, the statement said.
No information concerning the exact timeframe for the interview will be provided, it said, and Isgren would give no interviews during her stay in London, it added.
Sweden issued an arrest warrant for Assange in 2010 following allegations from two women in Sweden, one who claimed rape and another who alleged sexual assault.
Assange has refused to travel to Sweden because he fears the country would send him to the United States, where an investigation is ongoing into WikiLeaks' release in 2010 of 500,000 classified military files on the wars in Afghanistan and Iraq and 250,000 diplomatic cables which embarrassed Washington.
He has long offered to be interviewed by prosecutors at the Ecuadorian embassy or by video link.
Swedish prosecutors had long insisted that he travel to Sweden to answer to the allegations, but in March they finally agreed to question him in London, marking a significant U-turn
in the case that had been deadlocked for nearly five years.
Assange's lawyer Per Samuelsson told The Local at the time that the Australian had described prosecutors' decision to question him in London as "a great victory"
Prosecutors said they had changed their stance because some of the alleged offences will reach their statute of limitation in August.