Sweden's Appeal Court will determine Friday whether WikiLeaks-founder Julian Assange should be kept remanded in custody "in absentia", a Swedish prosecutor told a rare press conference on Wednesday.

Marianne Ny, who is Sweden's Director of Public Prosecution, is the chief prosecutor in the Assange case but she has rarely commented on it in public. On Wednesday, she broke her silence by calling a press conference together with her colleague, prosecutor Ingrid Isgren.

However, little new information emerged during the news conference, which instead focused on running through the history of events since Swedish prosecutors issued a European arrest warrant for Assange after allegations of sexual assault related to his 2010 visit to Stockholm to give a lecture. He denies those claims.

The press conference in Stockholm came ahead of an investigative report on the Assange case, scheduled to air Wednesday by Swedish broadcaster SVT.

SVT posted a preview clip of its documentary where Assange declines to discuss the rape allegations.

He says the "proper place for that is in a formal statement to the Swedish prosecutor. ... That's something that she has avoided for six years."

Assange has been staying at Ecuador's embassy in London for four years since applying for asylum to avoid extradition to Sweden. While Ecuador says it has approved a Swedish request to question Assange at the embassy in London, Marianne Ny said there had been no development since the beginning of August.

"We were told by the Ecuador government that they have accepted our request to interview Julian Assange at the embassy in London, but so far we have heard nothing from them," Ny said Wednesday.