WikiLeaks founder Julian Assange could be cleared of three sex assault claims as the prosecution time limits are set to expire while he remains in hiding in London.

The Swedish Prosecution Authority confirmed three of the four allegations made against him in 2010 would reach the five-year expiry date, set out under the country's statute of limitations, within the next week.

The Australian has been living at the Ecuadorian embassy in London since being granted asylum more than three years ago while fighting extradition from the UK.

He is wanted for questioning over the sex claims by two women in Sweden, which he denies, but fears being extradited to the United States over secret documents published by the whistleblowing organisation.

A spokeswoman for the SPA said one allegation of sexual molestation and one of unlawful coercion would expire on Thursday, while another of sexual molestation would expire on August 18.

But an allegation of rape will not expire until 2020, the spokeswoman added, meaning the legal impasse could remain.

Assange has previously said he agreed to be interviewed by Swedish authorities inside the embassy, but he claimed in June the country's chief prosecutor had cancelled an interview appointment.

The SPA spokeswoman said: "The prosecutor still wants to interview him. The prosecutor still has not got permission from Ecuador."

But a WikiLeaks spokesman said it would be "absolutely ridiculous" if the rape case was to remain open.

Kristinn Hrafnsson told the Times: "It's quite obvious that the Swedish authorities waited all these years. He doesn't have to clear his name. He has been asking to be interviewed in London for five years - he has asked for this to be moved forward.

"It's come to a time to end this. That case should be dropped as well."

Claes Borgstrom, a lawyer representing one of the alleged victims, called the expiration of the allegations an "injustice".

He told the Times: "On one hand she wants him ... to answer to the allegations, and of course to be convicted. But on the other hand she is relieved that she will not have to stand in court."

A statement Ecuador's embassy on Monday 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."

Assange's legal team has estimated the cost of the round-the-clock policing of the embassy in Knightsbridge is now more than STG12 million ($A25.60 million).