Sweden’s court of appeal will debate on Friday whether to grant Julian Assange an open court hearing in his renewed campaign to rescind the arrest warrant against him.

The prosecutors in the case, Marianne Ny and Ingrid Isgren, took the unusual step of holding a press conference in Stockholm on Wednesday “to give a snapshot of the investigation”, although they stressed that they did not have anything new to say in the case.

The prosecutors are waiting for Ecuador to grant them a date to interview Assange in the Ecuadorian embassy in London, where the WikiLeaks founder took refuge more than four years ago to avoid a perceived threat of extradition to face espionage and other charges in the US.

The Swedish prosecutor Marianne Ny talks to the media about the Julian Assange case on Wednesday. Photograph: Fredrik Sandberg/EPA

Ny refused to interrogate Assange at the embassy but changed her mind in March last year after criticism from the appeal court.

After a first appeal against the arrest warrant was rejected by Sweden’s supreme court last year, Assange’s lawyers launched a fresh effort to have the arrest warrant rescinded when the United Nations working group on arbitrary detention ruled that Assange’s situation amounted to a deprivation of liberty and demanded that the UK and Sweden ensure Assange’s safety and compensate him for the period of his detention.

Documents submitted by Assange to the appeal court include an assessment of his physical and mental health by Dr Michael Korzinski, a clinical specialist in trauma.

Assange is expected to argue that conditions inside the embassy are in certain ways worse than those of a conventional prison, with the potential to cause “severe harm” both physically and mentally.

The appeal court judges Jan Öhman, Kerstin Elserth and Jonas Högström will hear a presentation of Assange’s appeal by the legal clerk Åsa Linghede in Stockholm on Friday, starting at 9am.

