LONDON (Agencies) - A lawyer for WikiLeaks founder Julian Assange has said that any prosecution of the whistleblowing website in the United States for espionage would be unconstitutional. But Jennifer Robinson denied reports that Assanges legal team believe a US indictment over WikiLeaks release of thousands of classified US diplomatic cables is imminent. Our position is that any prosecution under the espionage act would be unconstitutional and call into question First Amendment protections for all media organisations, Robinson told AFP. She added: We are taking legal advice on the possibility of prosecution in light of high profile public officials calling for his prosecution and rumours circulating in the US that a sealed indictment is being prepared, or may have already been prepared. But we do not think there are grounds for prosecution, nor have we seen any sensible explanation of which provisions would be relied upon. Assange is being held in a London jail as he awaits a second court hearing on Tuesday to consider an extradition request from Sweden, where prosecutors want to question him about allegations of rape and molestation. His lawyers claim the extradition moves are politically motivated. Ms Robinson said that she believes US prosecutors are finalising their case and charges could be imminent. Speaking to ABC News, Ms Robinson said she had heard a number of rumours from several different US lawyers, but added that she did not believe the Espionage Act applied to Assange, who is she added is currently in solitary confinement in Wandsworth prison in London.