Swedish prosecutors have been accused of "victimising" Julian Assange after it was revealed they had interviewed 44 people in the UK but were refusing to question the WikiLeaks founder in the London embassy where he is living.
Supporters said Mr Assange was being "singled out" after he agreed to be interviewed inside the Ecuador embassy over sex allegations in Sweden - which he denies.
The Australian has been granted political asylum by Ecuador but fears that if he goes to Sweden he will be taken to the United States for questioning about the activities of WikiLeaks.
A Freedom of Information request by the Hazel Press news organisation revealed that Sweden has been granted 44 requests to interview a witness or suspect in the UK since 2010.
Jen Robinson, a member of the Assange legal team, said important questions were now being raised.
She told the Press Association: "First, they refused to take his testimony while he remained in Sweden. Then they refused to hear it in the UK, saying it was illegal to come here. Five years later, after being rebuked by their own courts, they say they'll consider it.
"Now we find out that not only was it standard practice all along, but that 44 other people in the UK were interviewed by Sweden during this same time period.
"Instead of hearing what he had to say, the prosecutor chose to cast a shadow of suspicion over Julian by seeking his extradition. We offered his testimony from London before the arrest warrant was issued, and have continued to offer it since.
"The prosecutor could have - and should have - availed herself of this mechanism to progress the investigation. Denying him this possibility for five years is the original injustice that has enabled many more injustices in his case.
"Julian hasn't been charged, yet he is being punished."
Ms Robinson said the cost of the round-the-clock policing of the embassy in Knightsbridge was now more than £12 million.
"The situation could have been resolved five years ago, exactly as we said it could, by taking Julian's statement in the UK.
"Will the Cameron government spend another £12 million to detain a person who hasn't been charged, simply because Sweden refuses to make use of the mechanisms available to resolve Julian's case?"
Mr Assange has been living inside the embassy for over three years.
A statement by the Ecuador Embassy said: "The Embassy of Ecuador to the United Kingdom clarifies that on no occasion has any representative of the Kingdom of Sweden presented themselves at the embassy in relation to the Assange matter.
"The Republic of Ecuador already made the sovereign decision to grant the journalist Julian Assange asylum on 16 August 2012. At no point has the Republic of Ecuador asked the Kingdom of Sweden to grant Mr Assange asylum."
Human rights campaigner Peter Tatchell told the Press Association: "The Swedish prosecutors are guilty of double standards and victimisation. They've interviewed 44 people in the UK since 2010. Why not Assange? They are making an exception of him. He's being singled out and treated differently.
"It is wrong to deny Assange the option to be interviewed in the UK, which has been extended to others and which he has been offering for five years.
"The Swedish authorities are not applying the law about overseas interviews consistently and fairly. They are acting in an exceptional and discriminatory way towards Assange.
"Julian Assange has been in various forms of detention for five years, without ever having been charged with any offence. This amounts to pre-trial punishment and is a gross abuse of his human rights and the legal system."