WikiLeaks founder Julian Assange has failed to have a Swedish detention order overturned but is buoyed by the fact prosecutors have been criticised for allowing their sex assault investigation to stall.
The Court of Appeal in Stockholm on Thursday refused to set aside a detention order granted in late 2010 over allegations Assange molested and raped two women.
But in the process the court noted the investigation had ground to a halt.
"The failure of the prosecutors to examine alternative avenues is not in line with their obligation - in the interests of everyone concerned - to move the preliminary investigation forward," the court said.
Assange's legal team believes that warning means prosecutor Marianne Ny will now have to travel to London to interview Assange in Ecuador's embassy.
The 43-year-old has been holed up there since August 2012 when he was granted political asylum by the South Americans.
"The pressure on the prosecutor to do something has increased," Assange's Swedish lawyer Per Samuelsson told AAP.
"The Court of Appeal, so to speak, warns the prosecutor 'If you don't go now we will cancel the custody decision the next time'.
"That's how you can interpret it."
Mr Samuelsson said the court was "cowardly" not to cancel the detention order outright but hopes the Supreme Court will act in due course.
Assange has already instructed him to appeal Thursday's ruling.
"The Supreme Court might have the courage that the Court of Appeal lacked ... and stop this farce," Mr Samuelsson said.
Assange's legal team argues prosecutors have unreasonably dragged out the investigation by not interviewing him in the UK.
They insist the circumstances of his stay at Ecuador's diplomatic mission constitute a deprivation of liberty.
But the Court of Appeal stated "the fact is Julian Assange can leave the embassy if he so wishes".
The Australian was more successful arguing the detention order was disproportionate given it was issued four years ago.
The appeal court noted "higher demands must be made on the reasons put forward by the prosecutor in support of their request for detention, the longer the period of time that passes without the prosecutor moving the preliminary investigation forward".
But in the end it was swayed by the fact Assange was suspected of relatively serious crimes and could flee if the order and adjunct European arrest warrant were cancelled.
"These circumstances mean that the reasons for detention still outweigh the intrusion or other detriment entailed by the detention order.
"Thus there is, at present, no reason to set aside the detention order."
The court on Thursday further rejected Assange's request for copies of the text messages of the two women he's suspected of assaulting.
It said his defence team had been allowed to see them which meant his right to insight had been satisfied.
After losing a UK legal battle against extradition Assange entered the Ecuadorian embassy in June 2012.
The Australian fears if he goes to Sweden he'll be extradited to the United States and charged over WikiLeaks' release of classified documents.
