Stockholm (AFP) - Swedish prosecutors dropped a sexual assault probe against Julian Assange on Thursday after the time limit on the case expired, but still want to question the WikiLeaks founder about a rape allegation.

Britain, meanwhile, said it would make a formal protest to Ecuador for allowing Assange to continue to shelter under the protection of its London embassy.

British Foreign Minister Hugo Swire called the arrangement "an abuse of diplomatic relations" and "a growing stain" on Ecuador's reputation.

Ecuador retorted that Britain and Sweden's "inaction" was the reason Assange had not been questioned by prosecutors before the statute of limitations on the accusations expired.

Assange has been holed up since 2012 at Ecuador's embassy, which is under 24-hour police guard and close to upscale department store Harrods.

The 44-year-old Australian fears that if he leaves he could eventually face extradition to the United States and a trial over the leak of hundreds of thousands of classified military and diplomatic documents in 2010.

Swedish prosecutor Marianne Ny said she was "obliged to drop part of the investigation" because the statute of limitations expired after five years on one count of sexual assault and another of unlawful coercion.

A third allegation of sexual molestation will run out on August 18.

Ny still wants to question Assange over the more serious claim of rape, which carries a 10-year statute of limitations due to expire in 2020.

Assange has always denied the allegations by two Swedish women and insists the sexual encounters were consensual.

"I am extremely disappointed. There was no need for any of this. I am an innocent man," Assange said, in a statement issued after the prosecutor's decision.

He accused Ny of being "beyond incompetence" for failing to travel to the embassy to take his statement or to pledge he would not be sent to the US.





- Rows over questioning -





Britain's government said Ecuador's decision to harbour Assange had "prevented the proper course of justice".

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"I have instructed our ambassador in Quito to reiterate to Ecuador that the continuing failure to expedite the Swedish prosecutor's interview and to bring this situation to an end, is being seen as a growing stain on the country's reputation," Swire said.

But a member of Assange's legal team, Baroness Helena Kennedy, highlighted what she said was the weakness of the case against him.

"The evidence would never have stood in any court of law worthy of its name," she said. "The remaining allegation is just as unlikely to lead to conviction."

Under Swedish law, if suspects are not questioned before the deadline on a case expires, they can no longer be tried for the alleged crimes.

Prosecutors say they have been unable to gain access to Ecuador's embassy, despite repeated attempts.

"Since the autumn of 2010 I have tried to interview Assange, but he has been consistently evasive," Ny said in her statement Thursday.

Prosecutors had initially insisted he return to Sweden for interrogation but in March agreed to Assange's compromise offer to question him inside the London mission.

They say Ecuador stalled on approving the deal, but the Ecuadoran foreign ministry insisted Sweden and Britain had only themselves to blame.

The cause of the impasse is "the continued inaction by British and Swedish authorities for the nearly 1,000 days of his stay in the embassy," it said in a statement.

"During that time, the Ecuadoran foreign ministry's proposals and calls for dialogue have fallen on deaf ears."





- Cramped living quarters -





Claes Borgstrom, a lawyer for one of the two women who accused Assange of assault in 2010, said his client was trying to come to terms with the likelihood that the case will never be tried.

"She has always been ready to stand by her accusations and wanted to bring the case to court. But at the same time a weight has been lifted. This has been dragging on for five years and she wants to go back to her normal life," he told the daily Dagens Nyheter this week.

Assange has compared living inside the embassy to life on a space station.

His room, which measures 15 feet by 13 feet (4.5 by 4 metres), is divided into an office and a living area.

He has a treadmill, a shower, a microwave and a sun lamp and spends most of his day at his computer.